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Andy
Andy, Truck Diagnostic Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 1571
Experience:  International trucks, International, Maxxforce and Cummins engines, diagnostic, electrical, Hvac and refrigeration repairs
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Peterbilt 387 2012 cummins isx engine.Head lights + Signals

Customer Question

Peterbilt 387 2012 cummins isx engine.Head lights + Signals stop working after few minutes. When I leave truck off for couple hours ,work again but goes off after few minutes.
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Andy replied 1 year ago.

Hi there ! My name is Andy! Would a wiring diagram help ? If so , can we start with the full vin number please ?

Customer: replied 1 year ago.

Hello Andy

It is 386 peterbilt 2012 Vin 1XPHD49XCD139155

Expert:  Andy replied 1 year ago.
Here is the wiring diagram for the exterior lamps . It is in two halves because I enlarged it for better viewing .
https://www.dropbox.com/s/zgu6o3n7gzkjix4/headlight%201.png?dl=0
https://www.dropbox.com/s/l8nat5lsvf62rbr/headlight%202.png?dl=0
Customer: replied 1 year ago.

I need pin I/put + O/put for cab module for lights. Wiring is ok. I doubt CECU module. Need to check it .How to check?

Want to make sure before buying. It is expensive

Expert:  Andy replied 1 year ago.

There was one digit missing from your vin number. Can you recheck please ? Should be 17 digits in total. Then I could double check and make sure we have the right circuit diagram. Then if you believe the wiring is sound , and you have a sister truck of same year and make , you could try swapping the module from one to the other to see if the problem goes away. Otherwise , if you don't have the program on a laptop to test the inputs and outputs with , it is pretty difficult to confirm where the problem lies . you could power the outputs with a power source and disconnecting from the module and powering it yourself to confirm lights come on !

Expert:  Andy replied 1 year ago.

That would tell you that outputs are OK so problem lies with module , or input switches .

Customer: replied 1 year ago.

I don't have any other truck to swap.If I had I will do that first before putting question on Just answer

Customer: replied 1 year ago.

I don't have any other truck to swap.If I had I will do that first before putting question on Just answer

VIN 1XPHD49X6CD139155

Can you send me wiring diagram showing module outputs

Expert:  Andy replied 1 year ago.
I will try and send you them as soon as I get home from work if that's OK . almost done
Customer: replied 1 year ago.

ok

Thanks

Expert:  Andy replied 1 year ago.
No problem. See ya soon .
Expert:  Andy replied 1 year ago.
Hi there ! Just got home from work ! Had to stay late to finish a job . Anyway , I looked at the diagrams I sent you and they have the inputs and outputs you are looking for for the headlamps circuit .
Customer: replied 1 year ago.

That did not show o/puts on module

Expert:  Andy replied 1 year ago.

That is all that I see for that vin for headlamp wiring !

Customer: replied 1 year ago.

I did not get any help from this information.

I have to send the truck to dealer

one last try when the truck is not started lights are ok.

When I start truck all markers and signals and head lights goes off in 1 minute and will not com about 6-7 hours after shutting of the truck.

Any clue?

Expert:  Andy replied 1 year ago.

Sorry about that but that's all that i had on it ! I hope it's a quick and easy fix ! Good luck .

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