The P0812: Reverse Input Circuit fault refers to a malfunction in the reverse input circuit, which signals the transmission control module (TCM) when the reverse gear is selected. This issue can be caused by a faulty circuit, wiring problems, or a malfunctioning TCM.
P0812 – Quick Overview
| Code | Information |
|---|---|
| Meaning | P0812: Reverse Input Circuit |
| Is it serious? | Yes, if the reverse input circuit is malfunctioning, it can prevent proper engagement of reverse gear and affect drivability. |
| Possible causes | – Faulty reverse input circuit – Wiring or connector issues – Faulty transmission control module (TCM) |
| How to diagnose? | – Test reverse input circuit – Inspect wiring and connectors – Replace faulty components if needed |
P0812 Meaning
The P0812 code means there is a problem with the reverse input circuit. This circuit is responsible for telling the TCM when reverse gear is engaged. If the circuit fails, the vehicle may not engage reverse gear properly or the TCM may not receive the signal correctly, leading to drivability issues.
Step-by-step diagnostic guide
| Action | Description | Tools Needed |
|---|---|---|
| Check for Other Codes | Use an OBD-II scanner to check for any additional transmission-related codes that may help in diagnosing the problem. | OBD-II Scanner |
| Test Reverse Input Circuit | Use a multimeter or diagnostic tool to test the reverse input circuit for continuity and proper voltage. Ensure the circuit is within manufacturer specifications. | Multimeter, Diagnostic Scanner |
| Inspect Wiring and Connectors | Inspect the wiring and connectors leading to the reverse input circuit for any damage, corrosion, or loose connections that could cause circuit malfunction. | Flashlight, Multimeter, Safety Gloves |
| Check Transmission Control Module (TCM) | Test the TCM to ensure it is functioning properly and communicating correctly with the reverse input circuit. Look for any faults or errors in the module. | Diagnostic Scanner, TCM Testing Tools |
| Repair or Replace Faulty Components | If the reverse input circuit, wiring, or TCM is found to be faulty, repair or replace the defective components according to manufacturer specifications. | Replacement Parts, Wrenches, Screwdrivers |
| Clear the Code and Test Drive | After repairing or replacing components, clear the code using an OBD-II scanner and test drive the vehicle to verify that the reverse gear engages properly and the issue is resolved. | OBD-II Scanner |
| Recheck for Codes | After the test drive, rescan the vehicle to ensure the P0812 code has not returned. | OBD-II Scanner |
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I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko