Hard starting 6.5TD Tahoe continued...

[john8662]

Ok. First off, I had the 1214 code, so I needed to get the timing set correctly.

Well I found a shop willing to do it, the mechanic said he'd done it on several Hummers because he used to be a Hummer Technician, so I figured that's legit, should know something about the 6.5L.

The mechanic used an MT2500 scanner.

Here are the codes he pulled (after a clear):

0216 - P0216 Injection Timing Control Circuit
0748 - ??????????????????????????????????????????????
1214 - P1214 Injection Pump Timing Offset
1218 - P1218 Injection Pump Calibration Circuit
1641 - P1641 Malfunction Indicator Lamp (MIL) Control Circuit
1654 - P1654 Service Throttle Soon Lamp Control Circuit

Before the scanner I used was the freebie at Autozone, just a code reader, it only found the 1214, so I was surprised to see all the codes on the MT scanner.

He fiddled with the scanner for over an hour and finally gave up and summoned me from the waiting room (he wouldn't let me be any where near the truck while he was working).

He said he couldn't set the timing, and then showed me some values on his scanner. They were way out of whack, which made me think that the scanner isn't really giving him the right values. Mainly this is concerning the TDC offset (said -2.46), then another screen that said TDC offset too and is said a really wacky value of 8523 (or something close to that, not even possible).

The desired timing was set at 8.6

So, what's up with the codes here guys?

Mechanic's advice was that I needed to replace the APP module, then a new PMD because the resistor is likely missing. This could very well be so, it's still on the pump, so who knows. I'll put the FSD cooler and new PMD back on the intake for troubleshooting again.

I'm currently confused why an error code would exist with th 1641 and 1654 for the MIL lights, both bulbs are present and working (I replaced a bad one a week ago).

Unless there is yet another relay somewhere that's missing, like the DRL relay (*%%^'n prev owner).

[Warren96]

If memory serves me correctly, OBD-2 stores trouble codes in memory and sreves them up as a history with a time and date.Don't you have to reset the codes once you fix a problem? That would explain the last code. Have Autozone erase all the codes,and see wich set again.When i extended the plug for the FSD i added an external resistor to my wiring harness. Cost? 0$

[john8662]

0748 is figured out, it's Pressure Control Solenoid in the transmission.

Called Bill Heath and he gave me some great pointers on my timing code, and the fact that the rest of these may be the result of the fault in the pcm.

Great man to take the time to offer the advice over the phone!

I'm going to need to move my IP a little, then do the relearn with the k/o K/o method, but I have to CLEAR the codes first. Autozone won't even do it anymore, found that out already. I'm going to go ahead and buy autoenginuity. This thing can sit until it gets here, I'll jump in the 6.2.

J

[john8662]

Aww.. Life is good for the moment!

Ok, here is the skinny.

Code 1214, and it's gonna start poorly, thats a guarantee!

Got the code situation under control. After seeing the offset on the snap-on timing meter I was able to move the pump to the passenger's side a little more than 1/16" and tighten the bolts back up. Then, I installed my spare FSD and cooler on the intake with a for sure #5 resistor installed, because one of the codes points toward a bad or missing resistor on the pump-mounted driver. Then I drove down to autozone and had them clear the existing codes in memory. Then didn't start it and did the key-on key-off procedure that Heath described. After the procedure (took amost 7 minutes to complete) I started the engine, instantly no check light and the engine fired first flick of the key. The learn had been initiated and the computer and IP were close enough to play together, I let it idle for 10 minutes to make sure it met the 170* requirement for the learn to complete.

Cool! Engine starts great now, even with the 60g's!

Next, get the transmission behaving!

I dropped the pan and replaced the Pressure Control Solenoid ($84 at the dealer) in the transmission, along with new filter. Buttoned it back up and filled it to the gills with the red stuff again and went for a drive. Shifting was what I consider "normal." Smooth shifts under light duty on the accelerator, what it's supposed to do.

Why did the previous owner get rid of this one? Hmm, I wonder!

Dealer probably never did set the timing correctly on the IP if it has been replaced, still a mystery (cause it's soo old).

J

[tommac95]

Nice story (nice it ended well, that is).

Could you elaborate on (or link to) that key-on, key-off procedure?

[Bnave95]

Thanks John:)
When problem are told,not to often will we hear about the cure.
This goes in my file along with other problems fixed.

[john8662]

The Key-on Key-off procedure for resetting the computer and performing a manual TDC-learn on 96+ OBD-II.

Clear any codes in memory (codes that would normally set a trouble light).

Turn ignition on, press accelerator petal to the floor for 45 seconds (or 1 min).

Turn ignition off for 1 minute.

Turn ignition on, press accelerator petal to the floor for 45 seconds (or 1 min).

Turn ignition off for 1 minute.

Turn ignition on, press accelerator petal to the floor for 45 seconds (or 1 min).

Turn ignition off for 1 minute.

Turn ignition on, start normally, let sit and idle up to better than 170* mesured at the crossover (mine was already up to operating temp before starting this procedure).

Let idle for about 5 minutes.

Turn off, restart, should be fine if pump is in a relatively good position to set an offset. You'll need a scan tool to know where you are before you move it a bit, I had already witnessed that it was too far advanced. Otherwise you'll be doing trial-and-error (my other nick-name).

I'm not sure if this works on 95's or not, I'll ask Bill next time I get a chance to have a discussion with him, it may.

J