Electrical - Turn Signal, Horn, Parking light

[DavidC]

Agree with Bruce, ripping into a harness is not only time but can be risky. That is a last ditch decision. On another note being an Electrician it is hard for me to believe they would run ground wires from the front all the way back to the PCM area or what looks even further to S150. But I did not design or build it I guess.

 

[MMoyle]

Thanks for all the advice. I only had 20 minutes today to work on the truck but I was able to determine in that time that if I unplug the bulb of the right turn signal, I lose ground to the horns. I also determined that the ground going to the turn signal is not active either. So I guess that would mean I am not getting ground from G100?

 

[brucejohnson]

Thanks for all the advice. I only had 20 minutes today to work on the truck but I was able to determine in that time that if I unplug the bulb of the right turn signal, I lose ground to the horns. I also determined that the ground going to the turn signal is not active either. So I guess that would mean I am not getting ground from G100?

That is a great assumption with the symptoms displayed. The park/turn signal bulb would have been supplying a "loaded" ground circuit through the filaments, over to the left park/turn bulb's filaments to a good ground. So try a jumper from the right park/turn socket ground wire to a ground point (you can try any nearby screw head or bare metallic body/frame). I would also check the G100 terminal and wire from the lamp socket/horns by doing a continuity test on that one set of wires independent (disconnected) from the ground point. You are getting close for sure.

 

[DavidC]

Bruce 8W90-4 Connector Locations. Seem's the 99 and 2001 manuals state the same as I have posted

 

[brucejohnson]

Bruce 8W90-4 Connector Locations. Seem's the 99 and 2001 manuals state the same as I have posted

Thanks Dave! That "reply" was an event I did not send last night because I figured out your post, but apparently it was queued in the reply and did not delete from the thread no matter how many times I punched the delete button when I responded to MMoyle. Ah, technology at its finest...If it can be broken, I will find the way...

 

[DavidC]

Thanks Dave! That "reply" was an event I did not send last night because I figured out your post, but apparently it was queued in the reply and did not delete from the thread no matter how many times I punched the delete button when I responded to MMoyle. Ah, technology at its finest...If it can be broken, I will find the way...

If it isn't broken, send it to Washington

 

[MMoyle]

That is a great assumption with the symptoms displayed. The park/turn signal bulb would have been supplying a "loaded" ground circuit through the filaments, over to the left park/turn bulb's filaments to a good ground. So try a jumper from the right park/turn socket ground wire to a ground point (you can try any nearby screw head or bare metallic body/frame). I would also check the G100 terminal and wire from the lamp socket/horns by doing a continuity test on that one set of wires independent (disconnected) from the ground point. You are getting close for sure.

Per your advice, I made a ground jumper to the right park/turn signal ground and everything started working again (parking lamp, turn signal, and horn). That proves a ground issue for sure, so what would be the best next step? The G100 ground looks good and I cleaned it up just to be sure (not corroded and looked in good shape).

 

[brucejohnson]

Per your advice, I made a ground jumper to the right park/turn signal ground and everything started working again (parking lamp, turn signal, and horn). That proves a ground issue for sure, so what would be the best next step? The G100 ground looks good and I cleaned it up just to be sure (not corroded and looked in good shape).

Look at the wire where the terminal is at G100. Feel and look for bumps under the insulation. If contaminates (like battery fumes) have infiltrated at the terminal lug, the conductor (wire) may corrode and expand under the insulation causing a bumpy/crunchy condition. This is where careful thought comes into play. If the ground lug looks really good, it may be time to dig into the harness and check the splice S150. I am not one to probe the insulation along the wire and use a jumper from a probed point to ground as that open the chance of compromised wiring in the future, unless properly coated/sealed. Another last attempt to a repair would be splicing a ground wire from the three components and run a parallel ground circuit to G100. Although the potential exists for more snakes and gremlins to be induced by doing so. Go for a repair of the existing harness first...G100 terminal connecter lug and wire (2 to 3 inches back), both ends/connectors of the wiring harness for condition, then go mining in the harness for splice 150 if nothing bad is found. The diagram you found gives a great roadmap.
Good luck!

 

[MMoyle]

Look at the wire where the terminal is at G100. Feel and look for bumps under the insulation. If contaminates (like battery fumes) have infiltrated at the terminal lug, the conductor (wire) may corrode and expand under the insulation causing a bumpy/crunchy condition. This is where careful thought comes into play. If the ground lug looks really good, it may be time to dig into the harness and check the splice S150. I am not one to probe the insulation along the wire and use a jumper from a probed point to ground as that open the chance of compromised wiring in the future, unless properly coated/sealed. Another last attempt to a repair would be splicing a ground wire from the three components and run a parallel ground circuit to G100. Although the potential exists for more snakes and gremlins to be induced by doing so. Go for a repair of the existing harness first...G100 terminal connecter lug and wire (2 to 3 inches back), both ends/connectors of the wiring harness for condition, then go mining in the harness for splice 150 if nothing bad is found. The diagram you found gives a great roadmap.
Good luck!

Thank you Bruce! I will give it a go and let you know how I make out.

 

[brucejohnson]

Thank you Bruce! I will give it a go and let you know how I make out.

I forgot one item. By any chance do you know anyone with a TDR (Time Domain Reflectometer)? They are handy in situations like this. They are pretty darned expensive though, so I would probably assume the answer is no. Just had to ask...

 

[fest3er]

I forgot one item. By any chance do you know anyone with a TDR (Time Domain Reflectometer)? They are handy in situations like this. They are pretty darned expensive though, so I would probably assume the answer is no. Just had to ask...

I suspect you could use a laptop that has an ethernet adapter. *Sometime* they come with software that can test cabling, indicating how far away the breakage (or end) is. I've only used one with CAT5, but it might work with other types/gauges of wire.

 

[brucejohnson]

I suspect you could use a laptop that has an ethernet adapter. *Sometime* they come with software that can test cabling, indicating how far away the breakage (or end) is. I've only used one with CAT5, but it might work with other types/gauges of wire.

That would be interesting. Research and look-em-up time...off I go! WAIT, I am already "off"...

Ack-ack! (Martian talk...) Needs lots of resources for a primitive DIY TDR...I have most of it...but not where it would do MMoyle any good. I'm here, he's there... https://www.allaboutcircuits.com/projects/build-your-own-time-domain-reflectometer/
-OR-
https://hackaday.com/2016/04/15/poor-mans-time-domain-reflectometer/

 

[MMoyle]

I was able to solve my problem. It ended up being the G100 ground post. I borrowed a friend’s power probe ect2000 which allowed me trace the ground wire with a receiver and was able to determine that the wire was good all the way to the G100 ground. Once I was able to determine that, I took a closer look at the G100 wires and found one was broken off in the bundle (hard to see without taking the bundle apart) Once I fixed that, she was as good as new

Thanks to all of you for the sound advice. Now I can keep on truckin

 

[brucejohnson]

I was able to solve my problem. It ended up being the G100 ground post. I borrowed a friend’s power probe ect2000 which allowed me trace the ground wire with a receiver and was able to determine that the wire was good all the way to the G100 ground. Once I was able to determine that, I took a closer look at the G100 wires and found one was broken off in the bundle (hard to see without taking the bundle apart) Once I fixed that, she was as good as new

Thanks to all of you for the sound advice. Now I can keep on truckin

That is outstanding! Great to have some tools to help pinpoint the issue without a major surgery event. Glad it was an easy fix for you, and a learning experience for all involved.