Most of us have encountered the situation where you have gotten into the family chariot, put the key in the ignition and turned the key to start the engine and nothing happens or you may hear a click. Your day has quickly gone from not to bad to a mumble, mutter, mumble situation as you debate your next move. My suggestion is to take a deep breath and don’t panic. In automotive terms you have just encountered a “no start - no crank” situation and I will try and walk you through some basic trouble shooting steps to try and determine the problem. Please note if the engine cranks (turns over normally but does not start) then this information is probably not going to help you as you have encountered a different automotive situation – “a no start –engine cranks ok”.
Let us assume that the vehicle is a 1966 Chevrolet Impala with a 327 CID engine and Powerglide transmission and we were just ready to depart for a car show Saturday morning. This may seem very “old school” to someone with a newer computerized vehicle but it is my hope that this troubleshooting article will help the reader develop basic skills that can also be applied to much newer vehicles.
We have established that the engine does not start and we are probably going to be late for the car show but let us look for some clues to help us develop a plan to try and diagnose this problem. Do any lights illuminate on the dash such as oil pressure and the GEN light when the key is turned to the on (run) position? When the key is turned in the ignition does it rotate smoothly all the way to the right past the on (run) position to the start position? Is the transmission in Park? Set the parking brake and with your foot on the brake pedal if we move the shifter from Park to Neutral while the key is held in the start position does the engine attempt to crank? Does the dome light illuminate when the door is open? If you turn the headlights on do they work? These are all simple basic tests that can tell us if the battery is reasonably charged and that something simple like a switch being open when it should be closed is preventing the starter to work properly to crank the engine. If the head lights, dome light and dash lights illuminate that tells us that the battery is connected and at least charged enough to illuminate the lights – if the lights go out or become quite dim when the key is turned to the start position then the battery may be partially discharged or a poor connection may be causing the problem or if a click is heard when the key is turned to the start position there is the possibility that the starter or solenoid is bad. If a click is heard some people might automatically assume the starter or solenoid is bad but this may not be the case and since the wife has her heart set on a piece of new furniture I would strongly recommend that further tests be done before spending some hard earned money on a new starter.
After doing all the above tests in our situation we find the following results – no lights work, nothing happens when the key is turned to the run or start position – now what? It is like the vehicle is missing the battery so let us open the hood and do a few more tests after we have verified the key is in the off position, the transmission is in Park and the parking brake is set – remember SAFETY FIRST! An engine can begin to rotate and possibly even start if something is temporarily bypassed or shorted during testing! We have now opened the hood and observed that the battery is still physically in place and connected to the battery cables the same as it was the last time we checked the oil and coolant levels. We will require a few tools to do some more basic tests to try and determine why the vehicle appears dead electrically. A DC voltmeter, a 12 volt incandescent test light (rather than a LED test light) and a wiring diagram specific to the vehicle we are working on are necessities to do effective electrical troubleshooting. Some people may argue that they don’t need, don’t have or can’t find a wiring diagram and while the wiring diagram may not be required on this age of vehicle if you are very familiar with 1960’s and 1970’s Chevrolet products having the correct wiring diagram will save you time and money in my opinion. I was lucky enough to come across a wiring diagram that someone had posted on the internet – this is not always the case and sometimes it is necessary to spend money to obtain information such as wiring diagrams – this is usually a small investment versus purchasing and installing new electrical parts only to find the new part didn’t fix the problem – just my opinion.
The wiring diagram page I will post is one of three pages that is used to show the complete vehicle wiring diagram and shows the wiring under the hood. For our purpose this page is adequate and to make it easier for the reader to follow along I have added a red line for the portion of the circuit that is normally connected to the positive battery post.
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On the wiring diagram I have identified test points A, B, C, D, E, F, G and H that may prove useful as we move forward with our plan to determine the problem of why everything is “dead”. Since I prefer the path of easy (least resistance) testing and the battery is out in the open my first test points will be A and B – the positive and negative battery posts (as identified in the picture). If memory serves me correctly in 1966 Chevrolet was still using a top post (as opposed to a side post battery) battery style but I stand to be corrected. The first test will be with the voltmeter set to measure DC volts (on a 20 volt scale if the meter is not auto-ranging). Place the red test lead on the center (lead) portion of the positive battery post (A) and the black test lead on the center (lead) of the negative battery post (B) and observe the meter reading – it should be about 12.6 volts or higher if the battery is fully charged. In this case we get a reading of 12.5 volts – this may be acceptable and the battery may be nearing its end of life cycle so for now we will give it the benefit of the doubt. Next we will turn on the headlight switch on the vehicle and then do the same identical test and see if the battery voltage reading is still 12.5 volts. When we turn on the headlight switch this should place a load of approximately 10 amps on the battery if the circuit is working so this will determine if the battery is bad or if the head lamp circuit is open and no current is flowing to light the lights. Since the headlights worked the last time we used them and everything is dead we can assume that this is the next logical step without connecting extra test equipment. With the headlight switch on the lights are still not lit and the voltmeter still reads 12.5 volts – this indicates that the battery is probably ok and that the headlight circuit is open at some point. With the headlight switch still in the on position we will do a test with the meter between the actual positive battery post (A) and the terminal clamp on the positive battery cable by placing the red lead on one and the negative lead on the other – the meter should display 0.0 volts. We will do the same test at the negative battery post (B) and the terminal clamp on the negative battery cable with the voltmeter leads – again the meter should display 0.0 volts. As a last test at points (A) and (B) we will place the red meter lead on the positive cable terminal clamp and the black meter lead on the negative cable terminal clamp and observe the meter reading – it should now read 12.5 volts. What we are checking by doing these last three tests is to make sure that where the cable terminals connect to the battery posts there are good physical connections with no resistance between the actual battery posts and their respective cable terminals. If in the tests between the battery post and the cable clamps we had gotten a different then 0.0 volts (say 11.0 volts) this would indicate that there was a difference in voltage levels between where the positive and negative meter leads were connected to. In these two spots there should be no difference in voltage levels since each cable is connected physically to their respective post. The last test verifies that the voltage level difference (12.5 volts) that the circuit is seeing where it starts and ends at the cable clamps is the same as what is present at the actual battery posts. If both the positive and negative battery posts and their respective cable terminals had corrosion and neither was connected electrically to the battery posts you might still get a reading of 0.0 volts during the first two tests but you would not get a reading of 12.5 volts when the leads are attached to the cable terminals during the last test.
In this case we got the expected results displayed on the meter so we can now move on. For the next test we shall use the 12 volt incandescent test light rather than the volt meter since it acts as a better circuit load because it requires current to flow to make the incandescent bulb to light. Some people may just use the test light to do the battery post and terminal test and it will work for that usually but sometimes a voltage drop of as little as 1.0 volts can prevent a starter from turning over and cranking an engine. I find that a test light lit with 12.5 volts is almost the same brightness as a test light lit with 11.5 volts and it can be difficult to see a difference on a sunny day. I find it is usually easier to test for a bad ground connection than a bad positive connection – since there are only two ground points in this circuit that need to be tested lets do them first. I will connect the clip on the test lead to the positive battery cable terminal (A) and then I will touch the probe end to the negative cable terminal to make sure the test light illuminates the bulb brightly and it does – this verifies that our test light is working and that any point I touch the probe to that is grounded should result in the test light illuminating brightly. I will then touch the probe to the bolt or screw head where the 12 gauge wire terminal connects to the vehicle body – in this case just have to follow the wire and it will probably terminate at a screw threaded into the rad support. I will also touch the probe to the alternator case or frame since it should be a good ground point if the negative battery cable is providing a good electrical connection to the engine block. I may also touch the probe to a bolt head at another point on the rad support or inner fender well and verify that the light illuminates brightly. In this case we got a nice bright light at all the test points so we can now move on and test the positive portion of the circuit. To do this I will move the clip on the test light from the positive battery cable terminal to the negative battery cable terminal and touch the probe to the positive cable to verify the test light works ok. Next I will touch the test light probe to where the red wire connects to the positive post of the alternator at location (F) – there is usually a black rubber boot that will have to be pulled off to make sure the probe contacts the connection. After doing this we observe that the test light does not light. This indicates a problem since if we study the wiring diagram the terminal at the alternator is connected electrically to the positive post at the battery which indicates there is a problem between these two points - somewhere between (A) and (F) the circuit is open or has enough resistance they very little (if any) current is flowing as it should. Next we can touch the test light probe to point (G) on the horn relay and see if the test light now lights. We do this but the light does not light so now we will touch the probe to the stud on the junction block at point (E) and see if it now lights. It does so we know that current can flow to the stud and the problem is now between point (F) and point (E). If we observe the wiring diagram we can see that the 10 gauge red wire that connects to the junction block stud and feeds point (G) has an eye terminal as well as the 10 gauge wire coming from the battery cable positive terminal. Since we know touching the probe to the stud results in the light illuminating we know the terminal on the wire from the battery cable terminal is probably good but what about the terminal on the wire going to the alternator (F) and horn relay (G) areas? If we touch the probe of the test light to the terminal on the wire going to the alternator (F) and horn relay (G) it should light the test light as well but when we do this the test light does not illuminate. We have just found a problem (probably the only one) and where the terminal connects to the junction block stud and the other terminal is probably corroded or rusted to the point where a good electrical connection is no longer occurring. Odds are that if we take the terminals off the stud and clean up the surfaces of the terminals (or replace the terminals with new ones) the headlights will come on and the engine will probably start.
Some may ask why I did you not start at the junction block rather than the alternator stud and my response is that the alternator stud was a slightly easier spot to locate and access to test – this is just my opinion. Had I started at the junction block I might have just touched the stud which would make the light illuminate and I may not have checked the terminal on the wire going to the alternator and horn relay until I found that the test light did not light at the alternator stud connection. This was my decision and others might do it a different way and that is ok – use whatever approach works for you. The important things to remember is to first look for clues and then develop a logical and relatively simple plan to diagnose the problem and by testing determine where the problem in the circuit is located. There could have been another problem such as a corroded or broken wire, a blown fusible link, a bad connection at a terminal where the fuse block and harness connects at the firewall, a bad switch, etc. If this was the case we might have had to look at the second wiring page which covers the dash area of the vehicle but eventually we would have found it using the same type of testing procedures. The nice thing about doing electrical testing using these methods is you usually find and fix the problem fairly quickly and you do not spend a lot of money unnecessarily on electrical parts that are often expensive and may not fix the problem.
Hope you have enjoyed reading this journey into basic electrical troubleshooting and diagnosing and how it relates to a no start / no crank situation.
Let us assume that the vehicle is a 1966 Chevrolet Impala with a 327 CID engine and Powerglide transmission and we were just ready to depart for a car show Saturday morning. This may seem very “old school” to someone with a newer computerized vehicle but it is my hope that this troubleshooting article will help the reader develop basic skills that can also be applied to much newer vehicles.
We have established that the engine does not start and we are probably going to be late for the car show but let us look for some clues to help us develop a plan to try and diagnose this problem. Do any lights illuminate on the dash such as oil pressure and the GEN light when the key is turned to the on (run) position? When the key is turned in the ignition does it rotate smoothly all the way to the right past the on (run) position to the start position? Is the transmission in Park? Set the parking brake and with your foot on the brake pedal if we move the shifter from Park to Neutral while the key is held in the start position does the engine attempt to crank? Does the dome light illuminate when the door is open? If you turn the headlights on do they work? These are all simple basic tests that can tell us if the battery is reasonably charged and that something simple like a switch being open when it should be closed is preventing the starter to work properly to crank the engine. If the head lights, dome light and dash lights illuminate that tells us that the battery is connected and at least charged enough to illuminate the lights – if the lights go out or become quite dim when the key is turned to the start position then the battery may be partially discharged or a poor connection may be causing the problem or if a click is heard when the key is turned to the start position there is the possibility that the starter or solenoid is bad. If a click is heard some people might automatically assume the starter or solenoid is bad but this may not be the case and since the wife has her heart set on a piece of new furniture I would strongly recommend that further tests be done before spending some hard earned money on a new starter.
After doing all the above tests in our situation we find the following results – no lights work, nothing happens when the key is turned to the run or start position – now what? It is like the vehicle is missing the battery so let us open the hood and do a few more tests after we have verified the key is in the off position, the transmission is in Park and the parking brake is set – remember SAFETY FIRST! An engine can begin to rotate and possibly even start if something is temporarily bypassed or shorted during testing! We have now opened the hood and observed that the battery is still physically in place and connected to the battery cables the same as it was the last time we checked the oil and coolant levels. We will require a few tools to do some more basic tests to try and determine why the vehicle appears dead electrically. A DC voltmeter, a 12 volt incandescent test light (rather than a LED test light) and a wiring diagram specific to the vehicle we are working on are necessities to do effective electrical troubleshooting. Some people may argue that they don’t need, don’t have or can’t find a wiring diagram and while the wiring diagram may not be required on this age of vehicle if you are very familiar with 1960’s and 1970’s Chevrolet products having the correct wiring diagram will save you time and money in my opinion. I was lucky enough to come across a wiring diagram that someone had posted on the internet – this is not always the case and sometimes it is necessary to spend money to obtain information such as wiring diagrams – this is usually a small investment versus purchasing and installing new electrical parts only to find the new part didn’t fix the problem – just my opinion.
The wiring diagram page I will post is one of three pages that is used to show the complete vehicle wiring diagram and shows the wiring under the hood. For our purpose this page is adequate and to make it easier for the reader to follow along I have added a red line for the portion of the circuit that is normally connected to the positive battery post.
On the wiring diagram I have identified test points A, B, C, D, E, F, G and H that may prove useful as we move forward with our plan to determine the problem of why everything is “dead”. Since I prefer the path of easy (least resistance) testing and the battery is out in the open my first test points will be A and B – the positive and negative battery posts (as identified in the picture). If memory serves me correctly in 1966 Chevrolet was still using a top post (as opposed to a side post battery) battery style but I stand to be corrected. The first test will be with the voltmeter set to measure DC volts (on a 20 volt scale if the meter is not auto-ranging). Place the red test lead on the center (lead) portion of the positive battery post (A) and the black test lead on the center (lead) of the negative battery post (B) and observe the meter reading – it should be about 12.6 volts or higher if the battery is fully charged. In this case we get a reading of 12.5 volts – this may be acceptable and the battery may be nearing its end of life cycle so for now we will give it the benefit of the doubt. Next we will turn on the headlight switch on the vehicle and then do the same identical test and see if the battery voltage reading is still 12.5 volts. When we turn on the headlight switch this should place a load of approximately 10 amps on the battery if the circuit is working so this will determine if the battery is bad or if the head lamp circuit is open and no current is flowing to light the lights. Since the headlights worked the last time we used them and everything is dead we can assume that this is the next logical step without connecting extra test equipment. With the headlight switch on the lights are still not lit and the voltmeter still reads 12.5 volts – this indicates that the battery is probably ok and that the headlight circuit is open at some point. With the headlight switch still in the on position we will do a test with the meter between the actual positive battery post (A) and the terminal clamp on the positive battery cable by placing the red lead on one and the negative lead on the other – the meter should display 0.0 volts. We will do the same test at the negative battery post (B) and the terminal clamp on the negative battery cable with the voltmeter leads – again the meter should display 0.0 volts. As a last test at points (A) and (B) we will place the red meter lead on the positive cable terminal clamp and the black meter lead on the negative cable terminal clamp and observe the meter reading – it should now read 12.5 volts. What we are checking by doing these last three tests is to make sure that where the cable terminals connect to the battery posts there are good physical connections with no resistance between the actual battery posts and their respective cable terminals. If in the tests between the battery post and the cable clamps we had gotten a different then 0.0 volts (say 11.0 volts) this would indicate that there was a difference in voltage levels between where the positive and negative meter leads were connected to. In these two spots there should be no difference in voltage levels since each cable is connected physically to their respective post. The last test verifies that the voltage level difference (12.5 volts) that the circuit is seeing where it starts and ends at the cable clamps is the same as what is present at the actual battery posts. If both the positive and negative battery posts and their respective cable terminals had corrosion and neither was connected electrically to the battery posts you might still get a reading of 0.0 volts during the first two tests but you would not get a reading of 12.5 volts when the leads are attached to the cable terminals during the last test.
In this case we got the expected results displayed on the meter so we can now move on. For the next test we shall use the 12 volt incandescent test light rather than the volt meter since it acts as a better circuit load because it requires current to flow to make the incandescent bulb to light. Some people may just use the test light to do the battery post and terminal test and it will work for that usually but sometimes a voltage drop of as little as 1.0 volts can prevent a starter from turning over and cranking an engine. I find that a test light lit with 12.5 volts is almost the same brightness as a test light lit with 11.5 volts and it can be difficult to see a difference on a sunny day. I find it is usually easier to test for a bad ground connection than a bad positive connection – since there are only two ground points in this circuit that need to be tested lets do them first. I will connect the clip on the test lead to the positive battery cable terminal (A) and then I will touch the probe end to the negative cable terminal to make sure the test light illuminates the bulb brightly and it does – this verifies that our test light is working and that any point I touch the probe to that is grounded should result in the test light illuminating brightly. I will then touch the probe to the bolt or screw head where the 12 gauge wire terminal connects to the vehicle body – in this case just have to follow the wire and it will probably terminate at a screw threaded into the rad support. I will also touch the probe to the alternator case or frame since it should be a good ground point if the negative battery cable is providing a good electrical connection to the engine block. I may also touch the probe to a bolt head at another point on the rad support or inner fender well and verify that the light illuminates brightly. In this case we got a nice bright light at all the test points so we can now move on and test the positive portion of the circuit. To do this I will move the clip on the test light from the positive battery cable terminal to the negative battery cable terminal and touch the probe to the positive cable to verify the test light works ok. Next I will touch the test light probe to where the red wire connects to the positive post of the alternator at location (F) – there is usually a black rubber boot that will have to be pulled off to make sure the probe contacts the connection. After doing this we observe that the test light does not light. This indicates a problem since if we study the wiring diagram the terminal at the alternator is connected electrically to the positive post at the battery which indicates there is a problem between these two points - somewhere between (A) and (F) the circuit is open or has enough resistance they very little (if any) current is flowing as it should. Next we can touch the test light probe to point (G) on the horn relay and see if the test light now lights. We do this but the light does not light so now we will touch the probe to the stud on the junction block at point (E) and see if it now lights. It does so we know that current can flow to the stud and the problem is now between point (F) and point (E). If we observe the wiring diagram we can see that the 10 gauge red wire that connects to the junction block stud and feeds point (G) has an eye terminal as well as the 10 gauge wire coming from the battery cable positive terminal. Since we know touching the probe to the stud results in the light illuminating we know the terminal on the wire from the battery cable terminal is probably good but what about the terminal on the wire going to the alternator (F) and horn relay (G) areas? If we touch the probe of the test light to the terminal on the wire going to the alternator (F) and horn relay (G) it should light the test light as well but when we do this the test light does not illuminate. We have just found a problem (probably the only one) and where the terminal connects to the junction block stud and the other terminal is probably corroded or rusted to the point where a good electrical connection is no longer occurring. Odds are that if we take the terminals off the stud and clean up the surfaces of the terminals (or replace the terminals with new ones) the headlights will come on and the engine will probably start.
Some may ask why I did you not start at the junction block rather than the alternator stud and my response is that the alternator stud was a slightly easier spot to locate and access to test – this is just my opinion. Had I started at the junction block I might have just touched the stud which would make the light illuminate and I may not have checked the terminal on the wire going to the alternator and horn relay until I found that the test light did not light at the alternator stud connection. This was my decision and others might do it a different way and that is ok – use whatever approach works for you. The important things to remember is to first look for clues and then develop a logical and relatively simple plan to diagnose the problem and by testing determine where the problem in the circuit is located. There could have been another problem such as a corroded or broken wire, a blown fusible link, a bad connection at a terminal where the fuse block and harness connects at the firewall, a bad switch, etc. If this was the case we might have had to look at the second wiring page which covers the dash area of the vehicle but eventually we would have found it using the same type of testing procedures. The nice thing about doing electrical testing using these methods is you usually find and fix the problem fairly quickly and you do not spend a lot of money unnecessarily on electrical parts that are often expensive and may not fix the problem.
Hope you have enjoyed reading this journey into basic electrical troubleshooting and diagnosing and how it relates to a no start / no crank situation.
