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Daniel Wilson
Daniel Wilson,
Category: Medium and Heavy Trucks
Satisfied Customers: 4969
Experience:  Owner at DJ Wilson
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We have a recurring electrical ghost in a 2012 t700 with a

Customer Question

We have a recurring electrical ghost in a 2012 t700 with a paccar MX engine.
After being fixed for a week it has returned..
The sequence is this. Day 1, a spill valve code will pop up but no corresponding power drop or smoke. Code goes away on restart. Day 2-3 the dashboard display lights will begin to dim and brighten rhythmically if headlights or turn signal/hazards are in. Then the headlights will start flickering normal to dim, the turn signal lamps will burn or blow out, and the headlamps will eventually dim to non functional.
The control module for the headlights has been swapped and didn't fix problem. Tech said he found corrosion in headlamp plugs but I couldn't see any. Fuse popped during repair as well but tech thinks it went bad before, it didn't. We checked.no relays seem to get hot either. We can't find any bare spots on wiring.
What is likely causing this? I'm starting to think since the whole headlamp assy goes thru the turn signal assy on the steering wheel column, the turn signal arm assy might be shorting somehow?
Tech had it disconnected but didn't see anything.
I'm at a loss
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Daniel Wilson replied 1 year ago.

hi Steve, My name is***** will be glad to try to help. It sounds like you have a short either in the harness, Turn signal switch or a faulty turn stalk module that these circuits all run through which is located inside the center dash. Inspect these circuits and let me know

Customer: replied 1 year ago.
Please tell me that turn stalk module isn't the hideously expensive one that runs the lights, lol. It's 3k. I believe we swapped it with a good one last week to see if that corrected the issue, it did not
Expert:  Daniel Wilson replied 1 year ago.

Click on this link and see section 8 for the electrical system.

Troubleshooting

Expert:  Daniel Wilson replied 1 year ago.

Would that be the chassis node you were refering to?

Expert:  Daniel Wilson replied 1 year ago.

See PDF page 263

Expert:  Daniel Wilson replied 1 year ago.

Sorry 253 i meant

Customer: replied 1 year ago.
That's what I'm wondering, I don't have the service notes in front of me. I remember it ran almost exclusively the lights
Customer: replied 1 year ago.
That 'node' checked out I'm told
Customer: replied 1 year ago.
The blinking lights with turn signals has me thinking voltage is getting altered going thru the turn signal somehow
Expert:  Daniel Wilson replied 1 year ago.

Test the turn signal switch and harness and take a look at the turn stalk module

Customer: replied 1 year ago.
Passed visual first time, lol. But the contacts on the swing arm can get screwy if the arm is stressed. I lost a turn sig assy or two from that. I'll have them check
Expert:  Daniel Wilson replied 1 year ago.

Try a wiggle test on the turn switch and harness to see if it has an effect on the symptoms

Customer: replied 1 year ago.
Apparently after talking to my driver, the light eventually dim out but the marker lights will oscillate... Get this, if you turn everything off and shut down, give it 30 minutes, the headlights come back on.
Customer: replied 1 year ago.
Maybe the node isn't shorting out, it's getting overheated. So what would cause that other than a bare wire short?
Expert:  Daniel Wilson replied 1 year ago.

I agree as it says anything over 65 amps will overheat or overload the Node.... either a short in the harness, bad grounds or open circuit or corrosion causing high resistance in the circuit, A wrong style or incorrectly wired bulb in the circuit are all possibilitys

Customer: replied 1 year ago.
Ty, I'm having the tech run down that road right now.
Sorry, I've been on the phone with applicants
Expert:  Daniel Wilson replied 1 year ago.

I help on here in between jobs so I understand completely. Keep me posted.

Customer: replied 1 year ago.
They traced back another seemingly random spill valve code and guessed it had to be something between the cecu and the lights. In doing the trace the found a bad ground wire and replaced it. It also was grounding an external battery kill knob of sorts. They THINK they have it this time, guess we'll see
Expert:  Daniel Wilson replied 1 year ago.

Let me know. Thanks for the follow up Steve. It has been a pleasure to help. Please remember to rate my answers and service to you if you found the information helpful as that is how the site credits the experts for their time helping.

Customer: replied 1 year ago.
It lasted 3 days
Customer: replied 1 year ago.
Back to same issues, heating up those relays to smokin hot.
I'm having my driver replace the turn signal assy and the harness that attaches into the steering column harness.
Customer: replied 1 year ago.
I kind of wonder if the relays aren't damaged at this point as well
Customer: replied 1 year ago.
It's weird, the dimming will take a couple hours to start, then a couple to kills the lights as the turn signals oscillate and the dash flashes. The software update was already installed.
But why would the effect slowly burn and NOT pop the relays?
Expert:  Daniel Wilson replied 1 year ago.

Id take a close look at the harness and connector pins for anything indicating corrosion, shorts possibly related to moisture intrusion, etc. Test all connections to the turn stalk module and the module itself. Click on this link for the procedure. Please let me know when successfully have saved the info so I can shut down the link.

Turn Stalk

Customer: replied 1 year ago.
I think I have it, sent the link to me driver. Ty
This damned ghost is driving me nuts.
I'm told there was a software update that addresses this stuff but also told it wouldn't affect the dimming lights.
Unless the update fixes cooking relays, and the relays are now damaged, I don't know wtf to think anymore
Expert:  Daniel Wilson replied 1 year ago.

There are test procedures and test values for that turn stalk module. It could be a shorted module itself. That is what I am leaning towards if the harness has no shorts and the grounds are good.

Expert:  Daniel Wilson replied 1 year ago.

That link covers all that info for that module... I would do a thorough test on the module as covered in the manual and if any part of the test fails, replace the turn stalk module.

Expert:  Daniel Wilson replied 1 year ago.

Hi Steve, Did you get this resolved?

Expert:  Daniel Wilson replied 1 year ago.

Hi, did you get this resolved?

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