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Jerry Newton
Jerry Newton, GMC Technician
Category: GM
Satisfied Customers: 4508
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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No power to pigtail that connects to sensors, consistent,

Customer Question

no power to pigtail that connects to sensors
JA: Is the power loss consistent, or does it fluctuate?
Customer: consistent
JA: What is the model/year of your GM?
Customer: 2004 suburban 1500
JA: Are you fixing your Suburban 1500 yourself? What have you tried so far?
Customer: no. mechanic doing voltage checks
JA: Anything else you want the mechanic to know before I connect you?
Customer: no. light has been on for years. truck runs fine
Submitted: 2 months ago.
Category: GM
Expert:  Jerry Newton replied 2 months ago.

Which pigtail are you talking about? You have a light on? What is the trouble code or symptom?

Customer: replied 2 months ago.
harness from fuse box area to pigtail on intake . i think low voltage code. cant see voltage to knock sensors. should show volts when truck running ?
Expert:  Jerry Newton replied 2 months ago.

So you're chasing a knock sensor code/repair, yes? Those wires should not have any measurable voltage on them. The knock sensors themselves generate AC voltage that is read by the ECM.

If you have knock sensor codes, the fix is typically new knock sensors and a new harness. Very common failure and repair.

Customer: replied 2 months ago.
been there done that. gm sensors and harness
Expert:  Jerry Newton replied 2 months ago.

OK. Checking continuity between the connector and the ECM would be the next step. It's a very simple circuit, the wires just go the ECM.

What is the number of the trouble code you are chasing?

Customer: replied 2 months ago.
can you wait. mechanic test driving another vehicle.
Expert:  Jerry Newton replied 2 months ago.

I can wait. I am helping several people at once right now, just let me know when you're ready.