DTC 31: Open/Shorted Vehicle Speed Input Circuit
- Preform TCM DIAGNOSTIC CIRCUIT CHECK. Raise and support front of vehicle. Start and operate vehicle in drive ("D") at idle. Using a DVOM, measure voltage (backprobe) between TCM 14-pin harness connector terminals No. 11 (Light/Green wire) and No. 12 (Purple wire). See Figure. If reading varies between zero and 3 volts, and increases with wheel speed, go to next step. If reading is not as specified, go to step 3).
- DTC may be set by an intermittent problem. Inspect harness connections. Check for corroded, damaged or backed-out terminal pins. Check VSS shielding and shield ground for breaks, cuts or opens. Repair as necessary. If no problem is found, problem cannot be duplicated at this time.
- Disconnect VSS harness connector. Using DVOM, measure voltage between VSS terminals. If reading is between zero and 3 volts, and varies with vehicle speed, go to next step. If reading is not as specified, replace VSS.
- Turn ignition switch to LOCK position. Disconnect TCM 14-pin harness connector. Using a fused jumper wire, jumper terminal No. 1 (Purple wire) at VSS harness connector to chassis ground. Using a DVOM, measure resistance between chassis ground and TCM 14-pin harness connector terminal No. 12 (Purple wire). If resistance is less than one ohm, go to next step. If resistance is not as specified, repair open in Purple wire.
- Move jumper wire to terminal No. 2 (Light Green wire) at VSS harness connector. Using a DVOM, measure resistance between chassis ground and TCM 14-pin harness connector terminal No. 11 (Light Green wire). If resistance is less than one ohm, go to next step. If resistance is not as specified, repair open in Light Green wire.
- With DVOM still connected, remove jumper wire. If DVOM displays infinite resistance, check for poor connections at TCM. If connections are okay, replace TCM and retest system. If DVOM does not display infinite resistance, repair Light Green wire for a short to ground between TCM and VSS.