P1790 GMC Code - Transmission Control Module Checksum
Quick Answer
The P1790 GMC code indicates a problem with the Transmission Control Module (TCM) checksum. Common causes include Faulty TCM, Damaged wiring, Corrupted TCM program. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P1790 GMC indicates Transmission Control Module Checksum.
- Common causes
- Common causes include Faulty TCM, Damaged wiring, Corrupted TCM program.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
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Code P1790 GMC Description
The P1790 GMC code indicates a problem with the Transmission Control Module (TCM) checksum. The TCM is responsible for controlling and managing the transmission system in the vehicle. The checksum is a value calculated from the TCM's memory contents to ensure data integrity. When the checksum does not match the expected value, it indicates that there may be a corruption or error in the TCM's memory.
Common Causes of P1790 GMC
- Faulty TCM
- Damaged wiring
- Corrupted TCM program
- Incorrect programming
- Physical damage to the TCM
Symptoms of P1790 GMC
- Erratic shifting behavior
- Transmission slippage
- Harsh shifting
- Vehicle goes into limp mode
- Check engine light illuminated
How to Fix P1790 GMC
- Use a diagnostic scanner to read and clear the code
- Inspect the TCM and wiring for any signs of damage
- Check and update the TCM software if necessary
- Replace the TCM if it is found to be faulty
- Perform a relearn procedure to reset the TCM and adapt it to the vehicle's transmission system
Cost to Fix P1790 GMC
The typical repair costs for addressing a P1790 GMC code can vary depending on the specific cause of the issue. In general, replacing a faulty TCM can cost anywhere from $500 to $1000, including parts and labor. However, the total cost may increase if additional repairs or diagnostics are needed. It's important to note that labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate.
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Frequently Asked Questions about P1790 GMC Code
1. What does the OBDII code P1790 mean on a GMC vehicle?
P1790 indicates a Transmission Control Module (TCM) checksum error, meaning the TCM has detected inconsistencies or corruption in its data or programming.
2. What are the common symptoms of a P1790 code in a GMC?
Symptoms may include erratic shifting, transmission slipping, poor acceleration, the vehicle stuck in limp mode, or the check engine light turning on.
3. What causes the P1790 code to appear?
The code can be triggered by corrupted TCM software, a failed TCM, faulty wiring or connectors, or power supply issues affecting the TCM.
4. Can I drive my GMC with a P1790 code?
Driving with a P1790 code is not recommended, as it may lead to further transmission issues or leave the vehicle in limp mode, limiting performance.
5. How do you diagnose a P1790 code on a GMC?
Diagnosis typically involves scanning for additional codes, inspecting TCM-related wiring and connectors, testing the TCM's power and ground circuits, and checking for software updates.
6. Can a P1790 code be fixed by resetting the TCM?
In some cases, resetting or reprogramming the TCM may clear the code, but the underlying issue must be addressed to prevent recurrence.
7. How much does it cost to fix a P1790 code on a GMC?
Repair costs can vary, ranging from $100 for simple wiring repairs to $1,500 or more for TCM replacement, depending on the vehicle and diagnosis.
8. Does a P1790 code always mean the TCM needs replacement?
No, the issue may be related to wiring, software, or power supply problems, so a thorough inspection is essential before replacing the TCM.
9. Can a P1790 code be caused by a weak battery on a GMC?
Yes, a weak or failing battery can cause voltage drops or interruptions, potentially triggering the P1790 code.
10. Do I need to update my TCM software to fix a P1790 code?
In some cases, updating the TCM software can resolve the code if the issue is related to software corruption or outdated programming.
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