SPN 698/FMI 5
This diagnosis is typically Grid Heater circuit failed open.
Check as follows:
- Disconnect the Grid Heater harness connector.
- Turn the ignition ON (key ON, engine OFF).
- Measure the voltage between pin 2 of the Grid Heater harness connector and ground.Note: Voltage measurement must be taken with the first minute of key ON. If this was not done, cycle the key and recheck voltage.
- If the voltage is greater than 11 volts, go to step 6 .
- If the voltage is less than 11 volts, go to the next step.
- Cycle the ignition switch.
- Recheck the voltage between pin 2 of the Grid Heater harness connector and ground.
- If the voltage is greater than 11 volts, go to the next step.
- If voltage is still less than 11 volts, go to step 11 .
- Measure the voltage between pin 3 of the Grid Heater harness connector and ground.
- If the voltage is greater than 11 volts, go to step 10 .
- If voltage is less than 11 volts, go to the next step.
- Turn the Ignition OFF.
- Disconnect the MCM 120–pin connector.
- Measure the resistance between pin 3 of the Grid Heater harness connector and pin 92 of the MCM 120–pin connector.
- If the resistance is greater than 3 ohms, repair open between pin 3 of the Grid Heater harness connector and pin 92 of the MCM 120–pin connector. Refer to “65.1.1 Verify Repairs” .
- If the resistance is less than 3 ohms, go to the next step.
- Measure the resistance between pin 1 of the Grid Heater harness connector and ground.
- If the resistance is greater than 3 Ω, replace the Grid Heater. Refer to “65.1.1 Verify Repairs” .
- If the resistance is less than 3 Ω, repair short to ground between pin 3 of the Grid Heater harness connector and pin 79 of the MCM 120–pin connector. Refer to “65.1.1 Verify Repairs” .
- Measure the resistance between pin 2 of the Grid Heater harness connector and pin 41 of the MCM 120–pin connector.
- If the resistance is greater than 3 Ω, repair open between pin 2 of the Grid Heater harness connector and pin 41 of the MCM 120–pin connector. Refer to “65.1.1 Verify Repairs” .
- If the resistance is less than 3 Ω, replace the Grid Heater. Refer to “65.1.1 Verify Repairs” .
Verify Repairs
Verify repairs as follows:
- Turn ignition OFF.
- Reconnect any electrical connections that were disconnected to perform the diagnosis.
- Clear codes with DDDL 7.0 or latest version.
ENGINE EXHAUST To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area. Engine exhaust is toxic. - Start and bring engine up to operating temperature (over 140°F/60°C).
- Verify operation is satisfactory and no warning lamps illuminate. If warning lamps illuminate, troubleshoot the codes.