P2608

P2608-HIGH VOLTAGE AT THE #2 INTAKE AIR HEATER RELAY

P2608 - High Voltage At The #2 Intake Air Heater Relay:

WHEN MONITORED
When the ignition is on.

SET CONDITION
When the signal from the #2 Intake Air Heater output does not match the signal from the #2 Intake Air Heater feedback.

POSSIBLE CAUSES
- Loose connection
- Intake air heater relay
- Signal circuit shorted to battery negative
- ECM
- Intermittent condition

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. RELAY CLICKING
Ignition on, engine not running.
With the scan tool, actuate the Intake Air Heater relay.

Q: Can you hear the Relay clicking?

YES: Go To 2
NO: Go To 3

2. LOOSE CONNECTION
While the relay is clicking , wiggle the wiring harness and connectors.

Q: Does this interrupt the clicking?

YES: Repair the poor connection. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 3

3. INTAKE AIR HEATER RELAY
Turn the ignition off.
Remove the Intake Air Heater Relay.
Check connectors - Clean/repair as necessary.
Measure the resistance between the signal and return posts of the intake air heater relay.

Q: Is the resistance between 15 and 25 Ohms?

YES: Go To 4
NO: Replace the Intake Air Heater relay. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

4. SIGNAL CIRCUIT SHORTED TO BATTERY NEGATIVE
Disconnect the ECM harness connector(s).

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the signal circuit of the intake air heater relay and battery negative.

Q: Is the resistance greater than 100 K ohms?

YES: Go To 5
NO: Repair signal circuit shorted to battery negative. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

5. HARNESS SHORTED
Measure the resistance between intake air heater relay signal circuit and all other ECM circuits in the ECM connectors.

Q: Is the resistance greater than 100k ohms?

YES: Go To 6
NO: Repair the shorted harness.

6. ECM
Reconnect the ECM harness connectors.
Turn the ignition on.
Disconnect the intake air heater relay signal wire.

Q: Did DTC P0542 or 2608 set?

YES: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).
NO: Replace the ECM. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1