Hey everyone, i was checking out the engine harness on my 1987 350tpi camaro, and i noticed a blue ground wire that was taped up to the harness. It was located on the passenger side after the harness splits. I was wondering if anyone had input on what it is for. Any info would be greatly apperciated.

 

Sounds like the wire that runs to the knock sensor - have you checked it? It's between the #6 & #8 spark plug, on the BLOCK.

There's also the fan switch, located same place, only on the HEAD.

One is blue, one is black, I forget which is which - check both of those and make sure they have wires to them. No ground wire would ever be blue, always black for ground wires.

 

It's connected into the AC wiring but isnt in any diagram. Must be a diagnostic thing for techs

All later EFI 3rd gens seem to have it regardless of engine, always taped to the loom near the HVAC box not doing anything

Knock wiring is different and has a specific connector on the end. This has a silver ground ring

 

Thank you for the quick response. Now that i know that its suppost to be there i dont have to worry about it. Thanks again guys great help.

 

On some of the later A/C delete cars, that wire is supposed to be grounded as it tells the ECM that there is no A/C installed. However, for the 165? Don't know that one. I'll do some searching in the FSM I have for 87 and let you know.

 

Some ground wires are tan. Just so ya know.

 

Tan/wht you mean. Grounds switch between black, purple, black/white, tan/wht for different uses. I never bothered to open up each component to determine which goes to where for all cases but I have noticed some patterns. Purple is always sensor low ref, tan/wht is always from a large module to ground such as an ECM/PCM. Black and derivatives are used for pretty much anything else or as an override to the ppl and tan/whts above. Year/control system doesnt seem to make any difference either. Ive stripped V6/TPI's that had the combo colors and others just blacks. Same for LTx and LSx's with the LSx's seemingly using any color combo they have plentiful access to the day of assembly

The AC ground ring found taped to the harness from the factory was always blue, atleast on the 100 or so 3rd gen harnesses Ive stripped. This suggests it's not actually intended to be a permanent ground, but for something of a diagnostic use similar to the prime connector on the fuel relay

 

No, he means TAN... O2S ground wire is TAN (CKT 413)...

:edit: Looked it up in the FSM, and yes, that blue wire is grounded on NON-A/C cars. It's the CKT 732 FAN REQUEST wire or the A/C PRESSURE SWITCH input wire. "It's grounded to prevent the radiator fan from running at all times". Wish I had known about that a long time ago .