I have one of the early 2004 1/2 LLY engines. It came with the old style GPCM. This is causing a U0106 DTC code due to communication issues with this old controller. This Glow Plug Controller looks pretty straight forward as far as installing it myself. The dealer wants $100 for the controller, $79 to hook up his equipment to tell me it is bad (which I already know) plus another $85 to install it . Only 1 or 2 screws and 2 cables to install it. Can't see where it should take more than 15-20 minutes to install. I can do that myself but was wondering if this was something I should do or does the dealer have to do some kind of programing or flashing to make the new controller work properly? I know the controller talks to the computer..so just want to be sure I'm not trying something that is more than just a simple swap out. Thanks
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I don't think you have to do any programming. I will see if I can confirm.

6.6L LLY Engine DTC U0106 Resets or Will Not Clear - kw diesel glow plug glowplug SES control module communication start wait light #PIP3010A - (Dec 17, 2004)
6.6L LLY Engine DTC U0106 Resets or Will Not Clear
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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.

Condition/Concern:
Glow plug control module loss of communication, possible DTC U0106 set, and DTC will not clear. An internal problem with the glow plug controller may cause an intermittent DTC U0106 to set and the technician is unable to clear it using the Tech 2.

Recommendation/Instructions:
An updated Glow Plug Control module has been released to repair this concern. The part number for the updated module is 97379635.

.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Models:
(04 C2 C3 K2 K3 6.6 LLY Chevrolet Silverado GMC Sierra GMT800) and (04 C4 C5 D4 D5 E4 E5 6.6 LLY Chevrolet Kodiak GMC Topkick GMT560)

Glow Plug Controller Replacement
Removal Procedure




Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure in Engine Electrical.
Disconnect the glow plug controller electrical connector.



Disconnect the glow plug controller battery feed electrical connector (1).



Remove the glow plug controller bolts.
Remove the glow plug controller.
Installation Procedure
Notice: Refer to Fastener Notice in Cautions and Notices.





Install the glow plug controller.
Install the glow plug controller bolts.

Tighten
Tighten the bolts to 10 N·m (89 lb in).





Connect the glow plug controller battery feed electrical connector (1).



Connect the glow plug controller electrical connector.
Connect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure in Engine Electrical.

Thanks for the info...just 2 quick questions: !. Should I disconnect the neg on BOTH batteries and 2. Which cable is which? There is a round and square cable. Is the round one the GPC electrical connector or the GPC battery feed elictrical connector. Want to be sure I remove them in the correct order since it deals with a electronic controller. Thanks Again!!

Yes disconnect the negative battery cable on both batteries.

It doesn't matter which order your remove that battery cables .

Got beat again with my post. :mad:
Too many distractions tonight, (along with my speed typing skills). I’ll post this info anyways, I’ll feel better.

I’ve never replaced this controller, but this is what 2002 Helms says for Non-California Emission. Not sure about your 2004.5.
The manual says nothing about removing both battery grounds, but I would. The glow plug relay is fed from a 175A fuse, which isn’t going to quit, (very fast), if a wire or metal tool gets away from you.
CAUTION: Some torques values are lb inch, and some are lb feet.

-Remove IA Heater connector.
-Remove glow plug harness bracket bolt.
-Remove glow plug harness nut from left cylinder bank.
-Remove glow plug power feed wires from both cylinder banks.
-Remove glow plug controller nuts.
-Remove glow plug controller.
-Remove glow plug harness nuts from left cylinder bank.
-Remove glow plug harness from left cylinder bank.
-Remove glow plug harness nuts from right cylinder bank.
-Remove glow plug harness from right cylinder bank.

-Install glow plug harness to right cylinder bank.
-Install glow plug power feed to wire to right cylinder bank.
-Install glow plug harness nuts to the right cylinder bank, tightening to 18 lb in.
-Install glow plug harness to the left cylinder bank.
-Install glow plug controller.
-Install glow plug controller nuts, tightening to 18 lb ft.
-Install glow plug power feed to the left cylinder bank.
-Install glow plug harness nuts to left cylinder bank, tightening to 18 lb in.
-Install glow plug harness bracket bolt, tightening to 15 lb ft.
-Install IA Heater connector.

Reference 2002 Helms, page 6-1033, 6-1139 and 6-2824.

The Glow Plug Relay and the IA Heater Relay are controlled by the ECM, and appear to be ON or Off, so I doubt there’s any programming involved.

Again, I’ve never done one of these, but it seems straight forward.

There! I feel better now. :) :) :)

Thanks for the replies. I think I can tackle this job now.