Possible Speedometer and Abs fix for gear change

[HARDTRAILZ]

I do not think it would be since you did not touch them.

I do not think the pre-06 fix has been resolved.

[larryk]

Well, Im going to try and get a 4.10 ratio calibration OS uploaded to the PCM, have the tire size calibration done to the ABS module, and then, if none of that works.....pop the bulbs in the cluster and be done with it

Thanks

[HARDTRAILZ]

Did you read all the trying for that to happen before without working? I may have missed where someone got it, but I know several tried many options without success. Not to discourage you, but hate to see time wasted.

[larryk]

Ive searched and read a few threads....and see where there were issues. I seriously cannot believe that it is this difficult to solve, or hasnt been yet. Its three sensors that feed the systems....two in the front wheels (that wont be impacted by gear ratio) and one on the back of the xfer case. All it *should* be is a translation in the PCM/ABS modules of how many pulses per mile....which should match the same pulse ratio in the front hubs. There is no translation in the cluster....or BCM...... It has to be solvable.

[HARDTRAILZ]

Except that even having a member work with a GM Tech could not find where GM allowed for the right clicks to be made for it to work.

[larryk]

wEELLLL.....Guess Im going to be a Don Quixote (I feel the eyes rolling) and tilt at this windmill. Ill let you guys know how it goes.....or if its a crash and burn

So, tell me, all of you guys running gears on a 2006-....are you all running around with ABS/Brake lights on?

[HARDTRAILZ]

I wish you luck and hope you figure it out honestly.

I cant help on pre-06 lights, but my 06 has the ABS, Speedo, Stabilitrac all working accurately as it should

[TBYODA]

06+ pcm's can be programed for the correct gears and tires.

[HARDTRAILZ]

Sure can...

[larryk]

06+ pcm's can be programed for the correct gears and tires.

Have not seen a thread on that....can I use an 06+ PCM on my 04? Not sure if the 04 class2 bus is compatible...I'm sure the 06+ is CANBUS?

If it can be done, please send link to the thread...thanks again guys!

[PROSPHOTO]

What have you guys found to be the best programmer to make the changes?

[Shdwdrgn]

@larryk - No you cannot. In 2006 they changed the PCM from a P10 to a P12 model. Completely different pinout and internal code. Unfortunately those of us with 2005 and older models are stuck without some features, namely being able to easily change gears and tire sizes.

[escapepilot]

I had the same issue in my '04 EXT when swapping to 35s and 4.56s. I tried the Superchips programmer and it DID allow gear change settings, but it didn't solve my ABS issue. I wound up selling it because I also didn't notice any performance changes or increases in gas mileage w/ the mileage program.

I'm not 100% sure that my ABS issue is the gear change. Mathematically, changing from 3.73s to 4.56s w/ 35 should have the same final drive. The speedo is only off by 1-2 mph. I think my ABS issue is related to the hubs/sensors. When they changed the gears, they were generous with the grease and the reluctors are covered. I haven't found an answer to if that could affect the sensors yet.

[Shdwdrgn]

Did you read all the trying for that to happen before without working? I may have missed where someone got it, but I know several tried many options without success. Not to discourage you, but hate to see time wasted.

Actually I solved it on mine. Went from 3.42 to 4.10 gears, ABS issues were so bad that the ABS system was going into a panic mode almost every day driving to work. Having the GM dealer make adjustments helped some, it was only doing it once every week or two, but speedo was off by 20% and unusable. I found a VIN from a 2004 TB that had factory 4.10s, had them program that in, then used HPtuners to re-write all of my custom changes, readjust the shifting for the new gears, and fine-tune to smooth things out. Everything works perfectly now, speedo is dead-on.

If you get a tune file from a vehicle with 4.10s the information will transfer over, but HPT was unable to determine where the info was stored when I sent them the files.

[HARDTRAILZ]

Sweet...Congrats!

[bartonmd]

Like Jeff said, the '02-'05 can be changed, but it's not a click here or there kind of thing... It's a complete programed module from a vehicle that came with that gear ratio. For us, that means we're only good with 3.42, 3.73, and 4.10, because those are the only ratios that we came with. The real issue is that the early models are a 3-channel ABS (2 front hubs and the output of the T-case), so it calculates for the final drive ratio to get the pulses/mile for the rear and just straight up measures it for the front.

The '06+ don't have that problem because we have 4-channel ABS that all measures at the wheel. The ABS doesn't care what comes before the axles/hubs.

Mike

[v7guy]

There's been a few guys that have done the P12 swap, the unicorn is the 06 pcm from the I6 trucks, it still runs off of of serial data and is a P12 (the SS and 5.3 went to can-bus in 06 and the I6 trucks followed suit in 07). The early gauge cluster doesn't play well with the 06 pcm (fuel level, voltage etc is reversed... Reads full when empty for example, brake light stays on, etc) so it would need swapped, presumably an 06 cluster would work. The BCM apparently communicates just fine after the wires are moved... about a dozen if I remember correctly.
Swapping the entire engine harness minimizes greatly the repinning and you can pick em up for $100 give or take $25.

Oddly enough, I haven't seen any ABS codes with my 04 trailblazer yet and it's on 37s with 5.13 gears. I've had it up to about 35 or 40 so far... But I've never tried to tune anything on it and it's still programmed with stock tires and 3.42s.

[Shdwdrgn]

Erg... I was going to mention that about the possibility of swapping the wiring harness. The casualties of late-night posting I guess.

v7guy, since you seem to be the odd-man-out with regards to ABS failures, it makes me wonder about two possibilities -- 1) Perhaps something in your ABS system is broken and not reporting the failure? 2) Maybe your setup is just SO far out of scope that the systems said screw it and doesn't report the error? For what it's worth, when I was having those problems I did re-flash my PCM with the generic stock code just to see if it would help. It didn't.

[Jrgunn5150]

What have you guys found to be the best programmer to make the changes?

I had mine tuned by Jeremy of Lime-Swap.

[v7guy]

After last night it appears that I do have the issue, had her up to 42mph and I got the incessant chime along with the ABS/brake! light. Restarting cleared it. But apparently I just haven't had it fast enough prior to last night to show the issue.
Everything still appeared to work and at lower speeds I can still activate abs if slam the brakes hard. So everything is functioning.

So are we looking at the only solution being swap to a P12 and convert over to 4 channel abs? That's gonna suck.