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Grid heater not working

1633 Views 10 Replies 4 Participants Last post by  MGDoug3, 
MGDoug3
2003. I'm getting codes P0542 and P2608. I checked for continuity for the hot wire going to the grid heater solenoids and also the wires at the grid heater. Every thing checked out so I assumed I had two bad solenoids. I replaced them but I still have the same problem. With the key on, I'm getting no power to the grid heater. I check my battery connections and all were clean.

My next plan of attack is to borrow a scanner and see if I can get the solenoids to click. Has anyone had this problem before and how did you solve it? The truck has been starting ok without the heater cycling and I usually keep the truck plugged in on a timer but colder temperatures are coming in and I may not always be next to an electrical outlet.

Thanks for any help.
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rghavana
POSSIBLE CAUSES
LOOSE CONNECTION
INTAKE AIR HEATER RELAY
SIGNAL CIRCUIT SHORTED TO BATTERY NEGATIVE
ECM
INTERMITTENT CONDITION

Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P0542-HIGH VOLTAGE ON THE #1 INTAKE AIR HEATER RELAY.
Both codes point to same high voltage issue

Should try perform proper resistance testing, (no power to circuit, meter zeroed) could have continuity but wrong resistance.
I would check wiring/connections for issues by

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.
Is the resistance between 15 and 25 Ohms? new heaters but should rule out.
Yes ! Go To 4
No ! Replace the Intake Air Heater relay.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).

4 Disconnect the ECM harness connector(s). known issue, disconnect batteries first.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the signal circuit of the intake air heater relay and battery negative.
Is the resistance greater than 100 K ohms?

Yes ! Go To 5
No ! Repair signal circuit shorted to battery negative.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).

5 Reconnect the ECM harness connectors.
Turn the ignition on.
Disconnect the intake air heater relay signal wire.
Did DTC P0542 or 2608 set?
All
Yes ! Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
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rghavana
IMO, Need to "Disconnect the ECM harness connector(s).
Double Check connectors known issue on 03 - Clean/repair as necessary.
Just want to Measure the resistance between the signal circuit of the intake air heater relay and battery negative.
Is the resistance greater than 100 K ohms?

For multimeter to read accurate resistance/ohms, really need to isolate signal circuit from other components/power , should always disconnect batteries if disconnecting ECM .
intake heater is controlled by ECM, on side of block, should be c2 connector rear most connector, pins 5(gray) and 6(white) for signal circuits.
On 03's , the PCM on firewall is mainly used for transmission control.
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