Without Scan Tool

When the TCM senses an abnormality in the input or output systems, the (D4) indicator light in the gauge assembly will blink.
When the Service Check Connector (located under the dash on the passenger side) is connected with the special tool as shown, the (D4) indicator light will blink the Diagnostic Trouble Code (DTC) when the ignition switch is turned On.




When the (D4) indicator light has been reported on, connect the Service Check Connector with the special tool. Then turn On the ignition switch and observe the (D4) indicator light.




Codes 1 through 9 are indicated by individual short blinks. Codes 10 and above are indicated by a series of long and short blinks. One long blink equals 10 short blinks. Add the long and short blinks together to determine the code. After determining the code.
Some PGM-FI problems will also make the (D4) indicator light come on. After repairing the PGM-FI system, disconnect the BACK UP fuse (7.5 A) in the under-hood fuse/relay box for more than 10 seconds to reset the TCM memory, then recheck.

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 make note of the radio presets before removing the fuse so you can reset them.