[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.

 

[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).

 

[Cumminjohnson]

You might have already checked this but mine was out 3 weeks ago...through the code and check engine light. Checked under the hood checked everything. Then grabbed the terminals to see if they were hot or loose. my passenger side battery terminals needed replacing. Positive was so loose that it was melting and starting to make a point in the bottom of the terminal and starting burning a hole in the battery! Sometimes it’s usually a connection issue or weak battery’s.

Good luck with it.

 

[MGDoug3]

Before I started the test procedures, I throughly cleaned all battery and ground connections. Next. I went through the test procedures and didn't solve anything. On step 4, I didn't disconnect the ECM. I wasn't sure if that meant the ECM on the motor or another one. I have an Edge Insight and was worried about clearing out my maintenance schedule before I wrote it down.

I did disconnect the negative battery cable and check the ohms between the signal wire and negative battery post which read 140 ohms. Not sure if this is correct or not since I didn't disconnect the ECM harness. Can someone clarify if it is the ECM on the block?

I started the truck and checked all the battery cables for excessive heat and everything is ambient temperature checked with a temp gun.

It seems odd that the grid heater would go out all of a sudden. I tried to clean the ends that hook to the actual grid heater but the bolts feel like they're about to twist off and I'm afraid I'll snap the bolts off.

Truck is sitting outside in the cold so I decided to stop and report back. I plan to do a little more research tonight and pull the truck inside tomorrow. I'll borrow the scanner tomorrow as well and see if I can get the relays to click.

Luckily the truck does seem to start fine in the cold until it reaches the teens or below. I usually like to keep the truck plugged in just because it's easier to turn over.

 

[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.

 

[MGDoug3]

I disconnected the battery cables and the two connectors at the ECM and ohm'd out the signal wire to the battery. Both signal wires (one on each relay) measured 100K ohms. Since it's not greater, I'm assuming it's in the wiring?

 

[MGDoug3]

I went over all the wires and checked all the connectors I could find. I didn't see any broken, bare or corroded wires or connectors. I put everything back together but in a heated shop the air temperature was too hot to try to kick on the grid heater. After the truck sat outside for a bit, the codes came back.

 

[MGDoug3]

I did a little more trouble shooting. I took the signal and ground wires off the solenoids and jumped the relays and made the relays click. Next I took the intake horn off and had someone use a use a infrared gun to read the temperature. It got over 300 degrees. I forgot to take off the ground on one of the relays but when I jump the signal post, the relay clicked on. That at least tells me the ground is good.

I believe the ECM isn't sending a signal. Besides throwing a possible code, can I or is it ok to use a push button on the hot side to cycle the grid?

Edit: Or is it easier to use the ground to the push button? Maybe it's a terrible idea but just trying to think of a plan to get the grid heater to work.

 

[PWong]

I did a little more trouble shooting. I took the signal and ground wires off the solenoids and jumped the relays and made the relays click. Next I took the intake horn off and had someone use a use a infrared gun to read the temperature. It got over 300 degrees. I forgot to take off the ground on one of the relays but when I jump the signal post, the relay clicked on. That at least tells me the ground is good.

I believe the ECM isn't sending a signal. Besides throwing a possible code, can I or is it ok to use a push button on the hot side to cycle the grid?

Edit: Or is it easier to use the ground to the push button? Maybe it's a terrible idea but just trying to think of a plan to get the grid heater to work.

Sure you can, it doesn’t matter the hot or ground side, use a push button to click in the relay.
But you have to make sure you can manually do exactly what the ECM does to operate the grid heater from key RUN, START,RUN to 15 mph.
The grid heater can sucks down both batteries easily if it’s running too long.:wink2:

 

[MGDoug3]

Thanks for the feed back. I figured I could use less wire grounding the switch. I was going to use a push button so the grid is only on when the button is pushed in. I've read how people used a manual grid heater before but that was on older trucks.

 

[MGDoug3]

I ended up and wired into the hot side of my gauge lights since it would save wire and already has a fuse going to the battery. Wired it up, pushed in the button and the relays came on. Everything seems to be working but it does throw two codes (P0541 and P2607 I think). The check engine doesn't come on though. That's good enough for me.

I did have someone earlier turn the key on for me while I checked voltage to the signal side of the relays and it was almost zero. I would like to thank everyone who helped me troubleshoot.