Wipers/drivers brake light and turn signal issues. Please help

[GMT400Frank]

So I recently purchased a 1994 C1500 Extended cab. Previous owner did an engine swap to another sbc 350 4 bolt.

I am having an issue where the wipers do not function in any capacity including sprayers. On top of that the drivers rear brake light and turn signal is not functioning but with the lights on the main tailight functions but still no brake light. Bought the truck with no ac hooked up and i know the blower motor is shot I assume thats not related.

I have:
replaced the wiper pulse circuit board.
Checked all grounds on the outside of the truck and found many that had failed or werent hooked up and replaced them including the one in the rear by the tailights on the frame.
All new headlights taillights and boards
Replaced headlight switch
Went through tailight wiring and repaired the issues i found.
Obd port ground is good as well but i do see a disconnect ground attached to the hood latch pull and not sure where to connect that. I cannot find any more ground locations under the dash to check.
I checked fuses and dont see any issues.

Passenger tailight functions as it should and so does the third brake light.

The cluster speedo battery and gas gauge work fine but no tach, no engine temp or oil pressure likely due to the swap.

Not sure what else to look for if figure out but this is getting the best of me and I have search the forums extensively looking for the cause/fix.

Any help is greatly appreciated!

 

[Drunkcanuk]

Check ALL your grounds!!!
Just watched a LS swap video on YouTube, and he had trouble with the wipers and signal lights. He had removed the front core support, and on the drivers side, he forgot a ground. Hooked it back up and fixed it all up.
So if the PO removed it for his swap, maybe they didn't hook it back up.

 

[GMT400Frank]

Check ALL your grounds!!!
Just watched a LS swap video on YouTube, and he had trouble with the wipers and signal lights. He had removed the front core support, and on the drivers side, he forgot a ground. Hooked it back up and fixed it all up.
So if the PO removed it for his swap, maybe they didn't hook it back up.

Will triple check but that specific ground you mention i have replaced with a new one. As well as the rear one by tailights. Alternator to battery. Battery to firewall battery to fender. frame to firewall. firewall to engine block. and fuel tank to body grounds. I am not sure any location of grounds inside other than the one by OBD port but as far as exterior grounds I am fairly certain I have replaced all of them. I am new to the GMT400 platform and did notice the juntion block on passenger firewall cover was off but I did not see any issues there with some quick voltage testing.

 

[scott2093]

Bought the truck with no ac hooked up and i know the blower motor is shot I assume thats not related.

One of the tests for ac clutch not working in the 93 manual mentions the wipers iirc.
May be relevant or not...but I think it was a ground wire fix...

edit...found the blurb...

 

[GMT400Frank]

One of the tests for ac clutch not working in the 93 manual mentions the wipers iirc.
May be relevant or not...but I think it was a ground wire fix...

edit...found the blurb...

Thank you I will check that. Is that a Chilton manual? Need to locate those wires and dont have the diagram for it.

 

[scott2093]

Thank you I will check that. Is that a Chilton manual? Need to locate those wires and dont have the diagram for it.

It's actually the 93 Sierra,Yukon,Suburban, Crew cab and 3500 HD Electrical and Diagnosis manual so not sure if it's of any use.?
Anyway, here's a photo of the ac circuit from that manual... there's only one ac circuit and another for the rear so I'm guessing it's the same across at least those trucks...
If it's useful and too blurry, I can take other pics. Just had this on my hard drive already...

 

[Drunkcanuk]

Thank you I will check that. Is that a Chilton manual? Need to locate those wires and dont have the diagram for it.

There are repair manuals located in the
"Engine performance + maintenance" section. 3rd down in the stickys

 

[GMT400Frank]

Thank you scott! I went and check the ground and it was secure. Now i bought this truck swapped and cannot for the life of me figure out these connectors and where they went to. I have a hunch that this is likely cause electrical gremlins for me but like i said before. I am new to the platform and to SBCs in general.

Any knowledge of where the should go or if they are needed would be a great help! They are all coming off main loom that is routed behind engine along the firewall and are coming out to passenger side of engine.

 

[GMT400Frank]

Thank you scott! I went and check the ground and it was secure. Now i bought this truck swapped and cannot for the life of me figure out these connectors and where they went to. I have a hunch that this is likely cause electrical gremlins for me but like i said before. I am new to the platform and to SBCs in general.

Any knowledge of where the should go or if they are needed would be a great help! They are all coming off main loom that is routed behind engine along the firewall and are coming out to passenger side of engine.

 

[GMT400Frank]

I did also notice it looks like there is a co nector missing of the ac compressor spades. Also a missing tie in on the junction block.