Preliminary Check

Attempt to start engine. If engine starts, go to step 1). If engine does not start, diagnose ignition system. See appropriate BASIC TESTING article in ENGINE PERFORMANCE.

• F - BASIC TESTING - Geo
• F - BASIC TESTING - 1.6L - Suzuki 1.6L
• F - BASIC TESTING - 1.8L - Suzuki 1.8L

1. Inspect noise suppressor filter. See NOISE SUPPRESSOR FILTER under COMPONENT TESTING. Replace if necessary. If noise suppressor filter is okay turn ignition switch to LOCK position. Disconnect TCM harness connector. Turn ignition on. Using a DVOM, measure voltage between ground and TCM harness connector terminal No. 4 (Brown wire). If reading is 11-14 volts, go to next step. If reading is not as specified, go to step 5)
2. Inspect TCM harness connector terminal No. 4 (Brown wire) for poor terminal contact. Repair as necessary and retest system. If connection is okay, go to next step.
3. Turn ignition switch to LOCK position. Reconnect TCM harness connector. Clear DTCs. See CLEARING TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine and run for 5 minutes. If DTC P0725 resets, go to next step. If DTC P0725 does not reset, fault is not present at this time. Check for an intermittent problem. See DIAGNOSTIC AIDS.
4. Replace noise suppressor filter with a known-good unit. Clear, then recheck for DTCs as noted in step 3). If DTC P0725 resets, replace TCM. If DTC P0725 does not reset, replace noise suppressor filter.
5. Disconnect noise suppressor filter harness connector. Using a DVOM, measure resistance between ground and TCM harness connector terminal No. 4 (Brown wire). If resistance is 2 ohms or less, repair Brown wire for a short to ground between TCM and noise suppressor filter. If resistance is not as specified, repair open or high resistance in Brown wire between TCM and noise suppressor filter.