Another mystery wire.

[DeCaff2007]

So, to get a wider immediate audience on this, I'm making a new thread instead of updating my V8 swap.

Who can identify this mystery wire and what it's supposed to plug into? First person who says O2 sensor, I hate to burst your bubble, will be incorrect. Or maybe I have the O2 sensor plugged into the wrong place?

Anyway, here goes nothing:

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[Jeepwalker]

What yr truck? Your engine's orange? Cool

BTW does it look like it was ever hooked up? Some leads could have been for testing.

 

[DeCaff2007]

What yr truck? Your engine's orange? Cool

BTW does it look like it was ever hooked up? Some leads could have been for testing.

It's actually supposed to be red lol.

Yeah, it was plugged into the other side of the O2 sensor wire. I believe that to have been incorrect.

1989 model year. If you're going to peruse through the electrical service manual, I bid you good luck. I've been there, done that, came up empty.

 

[GrimsterGMC]

That looks like the one you disconnect to set the base timing. Can't remember what it's called.

 

[Jeepwalker]

I can go out and look at my 89... lol. Would that work?

 

[DeCaff2007]

That looks like the one you disconnect to set the base timing. Can't remember what it's called.

Been through that, too. That connector is further up on the firewall. It's intact and plugged in. I can take a pic if you like.

 

[DeCaff2007]

I can go out and look at my 89... lol. Would that work?

Yes, please. Is your 89 a V6 or a V8?

 

[Jeepwalker]

Yeah, a wider shot would help. Mine (5.7L) has a brown wire (same connector) that exits the harness near the lower L of the brake booster (looking *at* the truck), and goes to the .....well you said not to say it so... he he..

Did you snag a new V8 harness that you're working with? Did you happen to do a continuity check back at the ECU to see if it matches up to the ...um, well, I won't say the O-word..lol..

The base-timing wire on mine is a white spade-style connector by the coil.


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[GoToGuy]

Little tip: if your working in that area, it's a sure bet if drop something, a screw, washer, nut, zip tie end, peanut shells, cig' butt, it will magically defy gravity and fall in that hole.
Ask me how I know, magic is real.

 

[CumminsFever]

It appears to be the speed sensor wire for the muffler bearings!
A better view would help provide context for the thing. Wasn't there an a/c wire with a plug like that? It's been too long since I've seen under the hood of an 89.