D4 Indicator Light Circuit Troubleshooting

D4 Indicator Light Testing:

^ If a customer describes the symptoms for codes 3, 6, or 11, yet the b4 indicator light is not blinking, it will be necessary to recreate the symptom by test driving, and then checking the D4 indicator light with the ignition still ON.
^ If the D4 indicator light displays DTC other than those listed above or stays lit continuously, the TCM is faulty.
^ Sometimes the D4 indicator light and the Malfunction Indicator Lamp (MIL)/Check Engine light may come on simultaneously. If so check the PGM-FI system according to the number of blinks on the MIL/Check Engine light, then reset the memory by removing the Back-Up fuse in the under hood fuse/relay box for more than 10 seconds. Drive the vehicle for several minutes at speeds over 30 mph (50 km/h), then recheck the MIL/Check Engine light.

NOTE: Disconnecting the Back up fuse also cancels the radio anti-theft code, preset stations and the clock setting. Get the customer's code number and made note of the radio presets before removing the fuse so you can reset them.