'87 r10 wiring help

[jnickell41]

I have a couple of wiring issues on a new to me '87 r10 5.7L tbi.

I have found two loose wires in the engine bay, pictures attached. Tan/white wire appears to come out of the firewall near the steering column. Green wire is near firewall above driver side valve cover.

Also, when the headlight switch is on the passenger side blinker indicator in the dash stays on. When the headlight switch isn't on the blinkers/hazards appear to all be working properly. When the headlight switch is on the driver side works fine the passenger side blinks slower and only uses the dimmer of the two filaments. Should I be looking for an issue at the passenger side light, ground perhaps, or does this sound more like something at the headlight switch?

Thanks,
John

[pontgta]

Sounds like bad bulb on passenger side.

[jnickell41]

That's what I thought too but I swapped bulbs from side to side and same thing.
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[foamypirate]

Originally Posted by jnickell41

I have a couple of wiring issues on a new to me '87 r10 5.7L tbi.

I have found two loose wires in the engine bay, pictures attached. Tan/white wire appears to come out of the firewall near the steering column. Green wire is near firewall above driver side valve cover.

Also, when the headlight switch is on the passenger side blinker indicator in the dash stays on. When the headlight switch isn't on the blinkers/hazards appear to all be working properly. When the headlight switch is on the driver side works fine the passenger side blinks slower and only uses the dimmer of the two filaments. Should I be looking for an issue at the passenger side light, ground perhaps, or does this sound more like something at the headlight switch?

Thanks,
John

Tan/white wire is feed to the dual tank selector switch (may be not have a corresponding connector if you only have a single tank). If you look at the bulkhead, on the left you will see a tan/white going into the firewall. This is the 12v+ feed from the fuel pump relay/ECM. This goes through a fuse, and comes out the right hand side of the bulkhead, where it splits into two wires. One wire feeds to the selector switch on dual tank setups (this is the unplugged connector), and the other runs back to the driver side tank to power the pump for a single tank setup. Even on a dual tank setup, you'll have the tan/white that runs all the way to the tank, it will just be unterminated in the connector that it shares with the fuel gauge signal wire (pink).

The green wire is a 12v+ signal from the A/C to the ECM to bump up the idle and tell the ECM the A/C is on.

[jnickell41]

So since I don't have A/C or dual tanks I should be good for the "loose" wires.

Now to figure out the blinker issue.

[jnickell41]

A little more info. I removed the front marker lights and signal lights on both side. Turning on the head lights like this does not result in the dash indicator lighting.

Replaced all the lights after cleaning the sockets with electronic connection cleaner and no change. I did notice that the passenger side signal light never uses the bright filament only the dim. I suspect a bad ground or short in the bright filament circuit. It seems like everything on that side of the truck is on the marker light circuit, including the dash indicator.

Any common short locations in this circuit? Where do the signal lights ground?

Thanks

[Pontiac1976]

Any common short locations in this circuit? Where do the signal lights ground?

Should be on the rad support right side or the left side.

[87 STEPPER]

Have you replaced the flasher unit yet?

You may also want to remove the headlight switch and clean the terminals on the switch and connector with some contact cleaner and see what happens.

[jnickell41]

Just to close this one out. I found the ground contact inside the turn signal socket, the one that contacts the bulb base, has broken off.

Any suggestions in replacement sockets? Napa has an Echlin unit that looks ok.