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post #1 of (permalink) Old 08-22-2012, 06:58 PM Thread Starter
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78 Caprice wiring

Hi, have some wiring issues with 78 Caprice, main problem is tracing wires from one end to the other through the loom, eg: internal lights work from headlight control but not from door jam switches , a circuit diagram would be a big help, if someone has one for this car.
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post #2 of (permalink) Old 08-29-2012, 05:23 AM Thread Starter
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Have managed to fix my internal lighting problem, my next problems to fix are: Heater only blows cold air, does any one have any ideas as to what could be going on, or how the heater system works as it's a combination of electrical and vacuum, which is something i haven't seen before.

Second problem is the washers run all the time that the wipers are running, the pump isn't the usual 12v pump in the reservoir but instead a mechinal one attached to the wiper motor with a ratchet and with 5 wires plugged into it???? Any help will be appreciated.
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post #3 of (permalink) Old 08-29-2012, 02:18 PM
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Glad you fixed the dome light problem.

Heater blowing only cold air is most likely the heater core plugged up which you can change out under the hood. Least likely problem may be that the temperature control cable is not connected to the blend door. You will find the blend door behind the glove compartment and it should have the cable attached to it.

Wiper washer problem will require a new washer unit which bolts up to the wiper motor. I have changed a few of them out on my car. They last about 1 to 2 years before going bad again.

1977 Chevrolet Impala Sedan
1989 GMC C1500 Sierra ECSB
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