TC1 - Enter Output State Diagnostic Test Mode

Diagnostic Trouble Codes (DTC) 621, 622, 626, 629, 641 and 652 indicate solenoid did not change state when requested by the Powertrain Control Module (PCM).

DTC 566 or 629 indicates the CCS or SS3/4-4/3 circuits did not change state when requested by the PCM.

Possible causes:
- Damaged solenoid assembly.
- Open or shorted harness (internal/external).
- Damaged PCM.

NOTE: Do not use a STAR Tester for this step. Use a Analog Volt/Ohm Meter (VOM) or Digital Volt/Ohm Meter (DVOM).

- Disconnect electrical connector on the speed control servo, if equipped.

- VOM/DVOM on 20 volt scale.

- Connect negative test lead to Self Test Output (STO) circuit at Data Link Connector (DLC) and meter positive test lead to B+.

- Jumper STI circuit to SIG RTN at the DLC.

- Perform Key On Engine Off Self-Test until Continuous Memory DTC have been displayed. Quick Test Appendix (Detailed Testing Instructions)

- VOM/DVOM will indicate less than 1.0 volt when test is complete.

- Depress and release throttle.

- Does voltage increase?

Yes -- Remain in Output State test mode. Go to TC2. TC2 - Check Solenoid Electrical Operation

No -- Depress throttle to Wide Open Throttle (WOT) and release. If STO voltage does not go high, perform pinpoint test step QC1. Leave equipment hooked up. QC1 - Check For Codes 23, 53, 63, 121, 122 or 123