LB7 TCM communication - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Infidel 76 · 11-08-2017, 05:19 PM

Helping my son with his truck, has lost communication with TCM intermittently. He has temporarily got it working messing with harness going to ECM, but issue returns. It appears as though a previous owner did some repairs to the ECM harness in the past and concerns me. Wondering if anyone has pin out diagrams for the ECU connectors so I can verify they are as they should be, and should help me rundown the cause of his current issues.

Current issues show code for TCM communication loss, fuel gauge, tach, speedometer not working. Transmission won't shift out of third gear.

2001 2500HD Silverado - LB7 Allison AT

11-08-2017, 05:19 PM	#1
Infidel 76 Registered User Join Date: Aug 2016 Location: Staplehurst, Nebraska Posts: 1	LB7 TCM communication Helping my son with his truck, has lost communication with TCM intermittently. He has temporarily got it working messing with harness going to ECM, but issue returns. It appears as though a previous owner did some repairs to the ECM harness in the past and concerns me. Wondering if anyone has pin out diagrams for the ECU connectors so I can verify they are as they should be, and should help me rundown the cause of his current issues. Current issues show code for TCM communication loss, fuel gauge, tach, speedometer not working. Transmission won't shift out of third gear. 2001 2500HD Silverado - LB7 Allison AT



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