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I have a 1978 that I installed a later wiring harness into so I have blade style fuses ( 79-82 design ) I am installing a 2017 LT1 into it. The problem I am having is everything was ok with the old engine , but now that the new one is connected I don't have power to the a/c-heater fan or power windows. My gauges work interior lights,radio, etc all work. I can start and run the engine with no problems.
I looked at the fusible links and they don't look bad, ( still wondering what the white casings are for )
My shop manual shows 2 links, and neither one looks burned at all. I guess I need to remove the harness because it's too hard to check it on the ground , and check for continuity on all the wires while its out.
Any other ideas what may be the issue ?
Thanks ,
I have a 1978 that I installed a later wiring harness into so I have blade style fuses ( 79-82 design ) I am installing a 2017 LT1 into it. The problem I am having is everything was ok with the old engine , but now that the new one is connected I don't have power to the a/c-heater fan or power windows. My gauges work interior lights,radio, etc all work. I can start and run the engine with no problems.
I looked at the fusible links and they don't look bad, ( still wondering what the white casings are for )
My shop manual shows 2 links, and neither one looks burned at all. I guess I need to remove the harness because it's too hard to check it on the ground , and check for continuity on all the wires while its out.
Any other ideas what may be the issue ?
Thanks ,
Ed
The white capsules are the splice joints between starter harness & links.
You say you have ignition that would be one of the links, the other is a direct path to headlight switch.
At this point I would rule out the fusible links.
There is a circuit breaker with a pink wire coming out from one side in the fuse box. I haven't figured out how to pull it out yet since it doesn't have little lips along the sides like the blade fuses. The fuse for the a/c- heater is good also. I was running new wires through the firewall for the in tank pump and a couple of other things. I'm going to take the center gauges and speedo out and check all the wires back there next.
Electrical is sometimes a challenge, but I will figure it out eventually.
There is a circuit breaker with a pink wire coming out from one side in the fuse box. I haven't figured out how to pull it out yet since it doesn't have little lips along the sides like the blade fuses. The fuse for the a/c- heater is good also. I was running new wires through the firewall for the in tank pump and a couple of other things. I'm going to take the center gauges and speedo out and check all the wires back there next.
Electrical is sometimes a challenge, but I will figure it out eventually.
Thanks for the responses.
Ed
The later circuit breakers can be pulled straight out.
Electrical may not be your strong suit but we will figure this out!
There is a single Brown wire with a single connector near your HVAC controls on drivers side Marked On My Drawing Brown Arrow Surrounded by red Box.
Is that single connector connected from New main dash harness to your 78 A/C harness?
If those are not connected together you will NOT have power to the Function Control Switch and the fan will NOT run on low speed with ignition switch ON.
Here are the 78-79 circuit differences:
I was reading about Fusible Links a few years back and I learned that they actually "wear" while being used in the electrical system. As they age they can actually fail so it might be worth getting a couple and have a spare that you can store away for the random day they might fail. NAPA Auto parts stores frequently have them in the various gauge sizes. I have my spares stored in a dry envelope inside a vacuum sealed bag so they will last a bit longer.
The later circuit breakers can be pulled straight out.
Electrical may not be your strong suit but we will figure this out!
There is a single Brown wire with a single connector near your HVAC controls on drivers side Marked On My Drawing Brown Arrow Surrounded by red Box.
Is that single connector connected from New main dash harness to your 78 A/C harness?
If those are not connected together you will NOT have power to the Function Control Switch and the fan will NOT run on low speed with ignition switch ON.
Here are the 78-79 circuit differences:
I found the brown wire which wasn't connected. I connected it to a pink wire near the rear window defog switch, but no difference. WE are having a cool snap in Colorado, so I will try tomorrow and remove the center console for easier access. If I am reading the diagram correctly , there should be power at the brown wire.
Ed
I found the brown wire which wasn't connected. I connected it to a pink wire near the rear window defog switch, but no difference. WE are having a cool snap in Colorado, so I will try tomorrow and remove the center console for easier access. If I am reading the diagram correctly , there should be power at the brown wire.
Ed
I pulled the center console off and checked the brown wire( 2 brown wires going in connector) going in the switch connector and have no power when I turn the ignition on. I checked the circuit breaker and it's good. I will check all the connections under the dash next in case I knock one loose or forgot to plug it back in.
I pulled the center console off and checked the brown wire( 2 brown wires going in connector) going in the switch connector and have no power when I turn the ignition on. I checked the circuit breaker and it's good. I will check all the connections under the dash next in case I knock one loose or forgot to plug it back in.
Ed
That sounds like you checked for power at the function switch connector?
If so, that is NOT the single Brown wire & connector(s) I wanted you to look for...
The main dash harness travels along the transmission tunnel on the drivers side. The brown wire from 25amp HVAC fuse exits that harness just below the cigar lighter.
Find that brown wire and see if it is connected...
Figure B C125 is the connector from the A/C harness...(C=connector)
That sounds like you checked for power at the function switch connector?
If so, that is NOT the single Brown wire & connector(s) I wanted you to look for...
The main dash harness travels along the transmission tunnel on the drivers side. The brown wire from 25amp HVAC fuse exits that harness just below the cigar lighter.
Find that brown wire and see if it is connected...
Figure B C125 is the connector from the A/C harness...(C=connector)
Sucess !!!!! It was a bad connection at C125. I had checked it for power before and didn't have any , but did the double check and found it.
THANK YOU ,THANK YOU, THANK YOU .Now I can put it back together.
One more step forward instead of sideways.
fusible link bad ?
