Code 51, Switch Condition Signal

ECM receives signal from P/N start switch, A/C amplifier and idle contacts of TPS. ECM uses these input signals to determine condition of circuits when diagnostic connector terminals "TE1" and "E1" are jumpered. When diagnostic connector terminals are jumpered with engine running and Code 51 is not indicated, one or more of the input signals is not received by the ECM. Inspect all 3 circuits.

1. Checks for a problem with ignition switch on.
2. This checks for idle throttle signal at ECM.
3. This checks for a faulty Blue wire, ECM or a misadjusted or faulty TPS.
4. This checks if P/N system is functioning properly.
5. This checks for an open Black/White wire or a faulty ECM.
6. This checks if A/C system is operating normally.

Fig 1: Code 51 Schematic (Except GSi), Switch Condition Signal

Fig 2: Code 51 Flow Chart (Except GSi), Switch Condition Signal