another round of what are these wires?

[kmanrsss]

When i removed my 87 cab i labeled all the wires i disconnected. There were some that were already broken and or disconnected. Ive got 3 wires that run in the harness that goes behind the engine, and they come out of the harness with the fat red and little purple wire for the starter.  The colors in question are a dark blue wire, black with white stripe and a tan wire.  the other wires in question are a pink with black stripe and a brown wire that go to a 2 prong plug. the plug is the same style as used on the fuel pumps. it comes out of the harness at with the red, blue, green, and yellow wire that goes into the tbi unit. i don't see any open plugs around, but was wondering if it possibly went to the air pump which is no longer there. Ive looked at the schematics and am either missing them or there not there. I am probably missing them. thanks for the help.

[kmanrsss]

The black/whit stripe wire is spliced with 5 wires coming in, one coming out. Possible ground?

[bd]

Here is a partial answer:  (1) the blue wire at the starter probably connected to a knock sensor that screwed into the block water jacket in front of the starter; (2) the pink w/ black stripe is ignition, paired with the brown wire exiting the harness along with the injector wires probably connect to the 'missing' Air Management Valve and air pump; (3) w/o more info (maybe a pic), the black w/ white stripe is probably ground and may be paired with the tan wire (O₂ sensor ground) to the back of the right cylinder head.

[kmanrsss]

Black with white appears to be grounds. The tan wire rings out to the ECM and from what I can tell is also a ground. The dark blue wire comes off the electronic spark controller. It's the port closest the engine. My colors don't match the book at all. It looks like it goes to the knock sensor. I forgot that was there. Thanks

[kmanrsss]

got one more that ive got no clue on. It's orange and comes out of the wiring harness directly below where the throttle cable passes through the firewall. ive already got a wire on the oil pressure that is in the same harness as the O2 sensor, and the truck runs. thanks for the help

[bd]

Do you have an oil pressure gauge or light?

[kmanrsss]

Yes there is an oil pressure gauge.

[Captkaos]

I have 3 uncut 87 TBI harnesses.  Post a pic of your harness for reference and then of the wires in question.

This is mine after I unbolted everything:

[87454westernhauler]

got one more that ive got no clue on. It's orange and comes out of the wiring harness directly below where the throttle cable passes through the firewall. ive already got a wire on the oil pressure that is in the same harness as the O2 sensor, and the truck runs. thanks for the help

on my 87 i had i also had he same wire also not hooked up to anything at all. thought it was an extra wire that could have been for the oil light if it would of had dumy gages but it always bugged me.

[bd]

got one more that ive got no clue on. It's orange and comes out of the wiring harness directly below where the throttle cable passes through the firewall. ive already got a wire on the oil pressure that is in the same harness as the O2 sensor, and the truck runs. thanks for the help

The wire color in the image you posted appears more 'tan' than 'orange' and probably connected to the oil pressure sender for the 'dash gauge.'

[kmanrsss]

Bad picture of the wire itself but its orange once you trace it back to a clean spot. It's possible that it was never used as there is no label on it. Gonna dig a little more tonight. Thanks for the help so far.

[rsandusky]

Low pressure switch on the combination valve for the brakes maybe? look on the frame rail

[kmanrsss]

Rsandusky, that was my original thought but I've got that hooked up already.

[Captkaos]

Can you tell me which connector it comes out of at the firewall plug?  Pic of it in perspective?

[pholliday1]

Would also be helpful if your tank has dual tanks there are provision in the wiring harness for that option.