P0700 on GMC
Transmission Control System Malfunction
P0700 on GMC vehicles indicates transmission control system malfunction. Au7o has documented this code across 3 GMC models — most commonly on C/K 1500, Sierra 2500HD, Sierra 3500HD. P0700 is a general code indicating the transmission control module (TCM) has detected a fault somewhere in the transmission control system and has requested the check engine light be turned on. By itself it doesn't pinpoint the problem — it's an 'umbrella' code that tells you to look for additional, more specific transmission codes stored alongside it. The actual fault could be electrical, a sensor, a solenoid, or an internal transmission issue. You may notice harsh or delayed shifts, slipping, or the transmission going into a protective 'limp' mode. Typical repair costs on GMC range from $300 to $4,500, depending on the specific model and root cause.
Common Causes of P0700
- •Stored companion transmission codes pointing to the real fault
- •Faulty shift solenoid or pressure control solenoid
- •Low, dirty, or degraded transmission fluid
- •Faulty transmission speed or input/output sensor
- •Wiring, connector, or ground problems at the transmission
- •Failing transmission control module (TCM)
- •Internal transmission mechanical wear or clutch problems
- •Valve body fault or sticking valves
P0700 on GMC by Model
GMC C/K 1500(1 issue)
- 4L60E Automatic Transmission Failure1993-1998
Same 4L60E transmission issues as Chevrolet C/K. Sun shell failure, 3-4 clutch pack burnup, and worn input drum.
GMC Sierra 2500HD(1 issue)
- Allison 1000/2000 Transmission TCM Failure and Harsh Shifting2011-2025
The Allison 1000 (gas) and Allison 2000 (diesel) 6-speed automatic transmissions used in Sierra 2500HD/3500HD are widely regarded as extremely durable, but the Transmission Control Module (TCM) and solenoid pack do develop faults. Common issues include harsh 1-2 shifts, transmission sticking in one gear, slip codes, and the truck going into limp mode (3rd gear only). The Allison's proprietary Transynd fluid is critical — using non-approved fluid is the leading cause of premature solenoid wear. TCM software updates from GM address most calibration-related shift complaints.
GMC Sierra 3500HD(1 issue)
- Allison 1000 Transmission Control Module and Sensor Failures2008-2019
The Allison 1000 transmission paired with the Duramax diesel in 2008-2015 Sierra 3500HD trucks has a high failure rate for the Transmission Control Module (TCM). A class action suit was filed covering these years. Additional issues include input/output speed sensor failures causing no-forward/reverse conditions, and certain 2012 trucks built with incorrect thrust bearings.
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View P0700 across all makes →Frequently Asked Questions
What does P0700 mean on GMC?▼
P0700 stands for "Transmission Control System Malfunction." P0700 is a general code indicating the transmission control module (TCM) has detected a fault somewhere in the transmission control system and has requested the check engine light be turned on. By itself it doesn't pinpoint the problem — it's an 'umbrella' code that tells you to look for additional, more specific transmission codes stored alongside it. The actual fault could be electrical, a sensor, a solenoid, or an internal transmission issue. You may notice harsh or delayed shifts, slipping, or the transmission going into a protective 'limp' mode. On GMC specifically, this code is documented across 3 models.
What causes P0700 on GMC vehicles?▼
Common causes on GMC: Stored companion transmission codes pointing to the real fault, Faulty shift solenoid or pressure control solenoid, Low, dirty, or degraded transmission fluid, Faulty transmission speed or input/output sensor, Wiring, connector, or ground problems at the transmission. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0700 on a GMC?▼
Repair costs on GMC range from $300 to $4,500, depending on the specific model and root cause.
Which GMC models have P0700 documented?▼
Au7o has documented P0700 on 3 GMC models: C/K 1500, Sierra 2500HD, Sierra 3500HD.