Test Procedure
- JH1 CHECK THE CTO SIGNAL FROM THE PCM NOTE: Refer to SYSTEM WIRING DIAGRAMS for module and connector locations.
- Disconnect the instrument cluster harness connector.
- PCM connector connected.
- Key on engine running.
- Measure the voltage between the instrument cluster CTO circuit, harness side and battery negative terminal.
Is the voltage between 3 and 9 volts?
Yes No REFER to INSTRUMENT CLUSTER to continue diagnosis on the circuitry for the CTO. Key in OFF position.
GO to JH2. - JH2 CHECK THE CTO FOR A SHORT TO POWER IN THE HARNESS
- PCM connector disconnected.
- Measure the resistance between:
(+) PCM Connector, Harness Side (-) PCM Connector, Harness Side CTO VPWR CTO VREF
Are the resistances greater than 10K ohms?
Yes No Key in OFF position.
GO to JH3.Key in OFF position. REPAIR the short circuit to PWR. - JH3 CHECK THE CTO CIRCUIT FOR A SHORT TO GROUND
- Measure the resistance between:
(+) PCM Connector, Harness Side (-) PCM Connector, Harness Side CTO PWRGND CTO SIGRTN
Are the resistances greater than 10K ohms?
Yes No GO to JH4. REPAIR the short circuit to GND. - Measure the resistance between:
- JH4 CHECK THE CTO CIRCUIT FOR AN OPEN IN THE HARNESS
- CHECK the CTO circuit resistance.
Is the resistance less than 5 ohms?
Yes No GO to JH5. REPAIR the open circuit. - JH5 CHECK THE CTO CIRCUIT FOR INTERMITTENT FAULTS
- Lightly tap on the CTO and wiggle the harness connector to simulate road shock.
- Measure the CTO resistance between the PCM and the instrument cluster.
Is the resistance less than 5 ohms?
Yes No Key in OFF position. INSTALL a new PCM.
REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .Key in OFF position. REPAIR the open circuit.