P2609

P2609-NO VOLTAGE DROP SEEN FROM INTAKE AIR HEATERS

P2609 - No Voltage Drop Seen From Intake Air Heaters:

WHEN MONITORED
First 15 seconds of engine operation.

SET CONDITION
The ECM does not detect a voltage drop on the intake air heater circuit.

POSSIBLE CAUSES
- Intake air heater open
- Intake air heater ground open
- Open battery cable from intake air heater relay
- Battery cable open
- #1 Intake air heater relay
- #2 Intake air heater relay
- Intermittent condition

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. INTAKE AIR HEATER OPEN
Measure the resistance between the intake air heater supply and ground terminal on each intake air heater.

Q: Is the resistance less than 10 Ohms?

YES: Go To 2
NO: Replace the open Intake Air Heater. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

2. INTAKE AIR HEATER GROUND OPEN
Measure the resistance of the intake air heater ground circuit between the intake air heater terminal and the intake manifold cover ground connection.

NOTE: The intake air heater circuit is grounded through a conductive gasket on the top and bottom of the air heater (grey colored gaskets).

Q: Is the resistance less than 10 Ohms?

YES: Go To 3
NO: Repair the open Intake Air heater ground or replace both heater gaskets with the proper conductive gaskets.. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

3. OPEN BATTERY CABLE FROM INTAKE AIR HEATER RELAY
Measure the resistance of the battery cable between the intake air heater and the intake air heater relay for both intake air heaters.

Q: Is the resistance less than 10 Ohms?

YES: Go To 4
NO: Repair The open or high resistance battery cable from the intake heater relay to heater. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

4. BATTERY CABLE OPEN
Measure the resistance of the battery cable between the battery and the intake air heater relay for both relays.

Q: Is the resistance less than 10 Ohms?

YES: Go To 5
NO: Replace the battery cable from the battery to the Intake Air Heater Relay. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

5. #1 INTAKE AIR HEATER RELAY
Disconnect the #1 intake air heater relay signal wire.
Connect a jumper wire from the signal terminal of the #1 intake air heater relay to battery positive.

Q: Did the relay click when 12 volts was applied?

YES: Go To 6
NO: Replace #1 Intake Air Heater Relay. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

6. #2 INTAKE AIR HEATER RELAY
Disconnect the #2 intake air heater relay signal wire.
Connect a jumper wire from the signal terminal of the #2 intake air heater relay to battery positive.

Q: Did the relay click when 12 volts was applied?

YES: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).
NO: Replace #2 Intake Air Heater Relay. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1