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GMC lost communication

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3 years 1 month ago #47698 by jose.alers
GMC lost communication was created by jose.alers
2017 GMC Sierra 4WD 5.3 L83 Code U1501 How to diagnose this? Power and Grounds to ABS ok.

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3 years 1 month ago #47702 by Tyler
Replied by Tyler on topic GMC lost communication
To be clear, U1501 is setting as current in the EBCM, is that correct?

If not in the EBCM, which module is it setting in? Any other symptoms?

U1501 is LIN bus code. To diagnose it, we first need to know which module flagged the U1501, and which module it lost comm with.

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3 years 1 month ago - 3 years 1 month ago #47710 by jose.alers
Replied by jose.alers on topic GMC lost communication
U1501 LIN Bus (Symptom 00)
U1510
Last edit: 3 years 1 month ago by jose.alers. Reason: Another code came up

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3 years 1 month ago #47715 by Tyler
Replied by Tyler on topic GMC lost communication
Nice. That means there's a problem on the PCM LIN bus. Lucky for us, there's only one wire on this bus, and one device, the active grille shutter.

Find X105 in the left front of the engine compartment. It's an eight pin connector, near the left headlight. Pin #6 at that connector is a light green/violet wire. Backprobe pin #6, start the engine and measure voltage on that pin with a DMM. Report what voltage you find and we'll go from there.

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3 years 1 month ago #47752 by jose.alers
Replied by jose.alers on topic GMC lost communication
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3 years 1 month ago #47753 by Tyler
Replied by Tyler on topic GMC lost communication
Yep, you're on the right track. :lol: The highest voltage in that shot is 4.something volts, when it should be closer to 12V.

Next move is to disconnect the grille shutter module and recheck. If the voltage comes up closer to 12V, verify power and ground at the grille before replacing it.

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3 years 1 month ago - 3 years 1 month ago #47762 by jose.alers
Replied by jose.alers on topic GMC lost communication
Last edit: 3 years 1 month ago by jose.alers. Reason: Did not look right

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3 years 1 month ago #47763 by jose.alers
Replied by jose.alers on topic GMC lost communication
12 volts after grill shutter disconnected. Will check for power and grounds.
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3 years 1 month ago #47764 by Tyler
Replied by Tyler on topic GMC lost communication

jose.alers wrote: 12 volts after grill shutter disconnected. Will check for power and grounds.


Love it. B) If powers and grounds pass, stick a fork in it, 'cause it's done.
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3 years 1 month ago #47788 by jose.alers
Replied by jose.alers on topic GMC lost communication
Power and grounds ok. Thank you for your help on this.

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3 years 1 month ago #47791 by jose.alers
Replied by jose.alers on topic GMC lost communication
Code 1501. Gone for now. Now U1510 is set.
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3 years 1 month ago #47793 by Tyler
Replied by Tyler on topic GMC lost communication

jose.alers wrote: Code 1501. Gone for now. Now U1510 is set.


This is after you replaced the shutters? What brand of shutter assembly did you use?

Recheck your waveform at the light green/violet wire at X105.

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3 years 1 month ago #47798 by jose.alers
Replied by jose.alers on topic GMC lost communication
10.2

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3 years 1 month ago #47821 by Tyler
Replied by Tyler on topic GMC lost communication

jose.alers wrote: 10.2


10.2V? Could you post another picture of the capture?

This is after you replaced the shutters? What brand of shutter assembly did you use?

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