DTC 29, 35 & 36 w/lotta white smoke

[ucdavis]

Just started getting the above on a cold start. Anybody had similar & fixed same w/a glow-controller change-out?
I'm hoping the 35/36 is a result of failed glow/ignition & IP/PCM playing around trying to get engine started by jockeying the injection pulse, then reporting its own tactic. If not, I'm off the the stealer for a new IP.

[GARY PAGE]

UC the DTC36 I believe as you say may be the ECM struggling with the engine during a cold start. After I installed the cold weather mod the DTC 36 stopped and I mean went away. I was running the AC60G plugs so I needed a bit more pre-heat time. Before the mod when I got the DTC 36 it was only while the engine was missing and was noted by the SES lamp coming on during the engine miss at cold startup. After the miss stopped and she was hitting on all 8 the SES lamp went off; but of course the DTC was stored. The 29 is the glow plug controller code which will clear next time it works correctly. Are you sure all plugs wires are good, and each plug is pulling current? I know you know all the tricks on the fuel system like filter, air in the lines all of which can cause a DTC35 and 36; but check it one more time before you go to the stealer. If you want to do a quick test with out doing the complete cold weather mod just unplug the temp sensor on the water crossover when cold and see how she starts. It will extend the glow plug cycle, advance timing, rattle a bit and run about 1000 RPM. If you let her run more than 8 minutes that way she will set a temp sensor code so this is a test only.

PS I got your IP documentation and am trying to digest it.

Gary

[pannhead]

35/36 kiss of death as you already know..interesting question though if a "hard" start can cause a 35/36..well sounds like your thinking out loud, you're off to get a new IP :( ...only 25k on pump? was your pmd remote mounted that whole time? i have a crazy PMD cooler devise i should have wrapped up this weekend,projects keep me out out of trouble ;) ...post back if you find the answer to your question..good luck ;)

[ucdavis]

Pan- Yes, thinking out loud (and hoping out loud too). Remote fsd is the standard till I isolate a reason to change that. It is a new fsd, but I mounted it B4 the torque-the-nuts discussion here recently, so I need to check that. Only about 4K on this pump; changed OEM pump out myself in Mexico (no warranty service there; Service Manager in La Paz said "We never sell dat electronic chit down here") for a new pump from USDiesel in Colorado. I still have PMD mounted (unplugged) so I can replug for warranty service when needed.
Gary- I'm running JK plugs & no extended glow time. When these first went in it was regulation starts & no trouble, so I'm thinking something happened. Rig is in Arizona where temps are around 50F, so its not a cold start deal, gotta be hardware. I have a spare controller, but I think connections may be the culprit so I'll start there (incl. the 15 pin connector, etc.). Your experience w/36 is what I hypothesized & hope to be the case for me; it would be awfully clever of GM, though, to have a pulse-width modulation process outside the ordinary working bandwidth to get engine started, so I'm curious to see if that is the case (I wouldn't have bet on it w/out some evidence like this). On other topic- the articles take a few reads to fully digest what Steve Garrett had to say. You should come away w/a fairly full understanding of the IP operation by your 3rd perusal.
Thanks for the replies gents.

[GARY PAGE]

Yes, I as I went to bed last night and began to think of a list of things I would check. The code 29 glow plug controller fault as you know is caused by 1) controller output voltage less than systems by some margin like a couple of volts or 2) output voltage present when the ECM says turn off, both of which are electrical faults. That seems to be at the root of the bad start problem. Obvious thought is the controller contacts or a sticky solenoid, which drives them but it could be simpler. Second thought is the battery connection at the controller module including battery post connections as well and their grounds. You know when the plugs are on it a heck of a lot of current is flowing and as finicky as the electronics are on these trucks who knows what can happen when the systems voltage sags too much, so even the batteries could be suspect. I would without replacing the controller remove and clean battery post connections, check and boost charge both batteries, clean both the input and output connections at the controller and re-torque each, clean the connector at the controller and just for the heck of it put a wrench on the manifold bolts which ground connections are under and make sure they are all tight. Test again and if that fails you can check the voltage across the contacts with the plugs on and it should be near zero, it