Computer question

[itsallhistory]

I have a 1991 4WD 3/4 ton Suburban 5.7 350 4L80 transmission. Some time in the past a body from a 1990 2WD 2500 was put on the chassis. So, I guess you could call it a hybrid.

My question is, would problems occur if the computer is from the 2WD? If yes, should I look for a computer from a 91 4WD? I looked behind the glove box and the numbers I found are the following:

16154461
AWBP

Thanks.

Kevin

 

[Jims86]

I have a 1991 4WD 3/4 ton Suburban 5.7 350 4L80 transmission. Some time in the past a body from a 1990 2WD 2500 was put on the chassis. So, I guess you could call it a hybrid.

My question is, would problems occur if the computer is from the 2WD? If yes, should I look for a computer from a 91 4WD? I looked behind the glove box and the numbers I found are the following:

16154461
AWBP

Thanks.

Kevin

Whats your rear end gear ratio?
Should be ok if you have 4.10 or 4.56.
And all you need is another chip, not a whole computer.
I looked up your code, and it is infact for 2wd 3/4 and 1 ton models, but I dont see a problem as long as your gears are in that range, provided your tires are stock diameter.

 

[itsallhistory]

Not sure of the gear ratio. Where would I look for that? Tires are 265/75/16. I heard that in 1990 Suburbans still had 700R4 transmissions and then went to 4L80 in 1991. I wondered if the difference would cause a problem if this were the case.

Where could I get a new chip and what reference numbers would I use to find the right one for a 1991 V2500? Thanks.

 

[Jims86]

Not sure of the gear ratio. Where would I look for that? Tires are 265/75/16. I heard that in 1990 Suburbans still had 700R4 transmissions and then went to 4L80 in 1991. I wondered if the difference would cause a problem if this were the case.

Where could I get a new chip and what reference numbers would I use to find the right one for a 1991 V2500? Thanks.

AXXZ or BAJW should be good.
you would have a 1227747 ecm if it was from a truck with a 700r4, and your 4l80 would not be shifting.
The ecm you have now. is correct for the TBI 350, And 4l80.

 

[itsallhistory]

So, get the AXXZ or the BAJW prom and replace put it in the computer I have in the Sub and I should be good to go? What is a good source for finding one?

4L80 is shifting fine.

Thanks for the info.

 

[Jims86]

So, get the AXXZ or the BAJW prom and replace put it in the computer I have in the Sub and I should be good to go? What is a good source for finding one?

4L80 is shifting fine.

Thanks for the info.

You should get ahold of Dave at [email protected] for that...he may have a tune for it already.
But, find out your gear ratio first. I dont think the chip cares if the truck is 4wd or not.
If the trans is shifting fine, just run what you have, it wont mess anything up.

 

[itsallhistory]

Thanks.

 

[Jims86]

Your welcome!

 

[bucket]

The chip has to be from another '91, or the trans wouldn't work. There weren't any 4l80e's in the '90.

 

[Jims86]

The chip has to be from another '91, or the trans wouldn't work. There weren't any 4l80e's in the '90.

His 4461 ecm number is just another service number for the 7060 ECM. Numbers probably superceeded like,they always do, semmingly after only anfew years.
His ECM is most likely from the 4wd. Even though the look up for his bcc says 2 wd, it is also listed for download for G,P(vans) and R and V models.
I say Hakunamatata....just drive it the way it is.
The 2wd chip wont cause the cruise acelleration issues that we are discussing on another thread.

 

[itsallhistory]

I think I have the problem solved (fingers crossed)...As a last resort I cut off the catalytic converter and replaced it with a straight pipe. It's been three days and no hesitation/power loss issues yet. From what I've read, the cat must've been close to completely gone. Thanks for all the information.

 

[oneluckypops]

not going to argue with you jim cause you know your ****. but i will add a little on the 2wd ecm being used in a 4wd.
Only probelm I could see is if the truck had 4 wheel ABS, which i know it doesn't but wanted to point it out anyway.

ECM receives a signal when 4wd is commanded then tells the ABS module of the change in driving style, if it didnt then fault codes would be stored for different wheel speeds from tire slipping.

 

[Jims86]

not going to argue with you jim cause you know your ****. but i will add a little on the 2wd ecm being used in a 4wd.
Only probelm I could see is if the truck had 4 wheel ABS, which i know it doesn't but wanted to point it out anyway.

ECM receives a signal when 4wd is commanded then tells the ABS module of the change in driving style, if it didnt then fault codes would be stored for different wheel speeds from tire slipping.

Yeah, your right...I dont think about that stuff in a square though..GMT400 on the other hand...but i think those were only rear abs, right?

 

[HotRodPC]

Not sure of the gear ratio. Where would I look for that? Tires are 265/75/16. I heard that in 1990 Suburbans still had 700R4 transmissions and then went to 4L80 in 1991. I wondered if the difference would cause a problem if this were the case.

Where could I get a new chip and what reference numbers would I use to find the right one for a 1991 V2500? Thanks.

Looks like Jim has you hooked up on the computer part of this. Stick with him for that purpose. As far as trans and it's really a moot issue for you, but the 3/4 ton and 1 ton trucks and Burbs has Th400 NON OD 3 speed automatics, not a 700r4. The 1/2 tons did indeed have the 700r4 though.

 

[HotRodPC]

not going to argue with you jim cause you know your ****. but i will add a little on the 2wd ecm being used in a 4wd.
Only probelm I could see is if the truck had 4 wheel ABS, which i know it doesn't but wanted to point it out anyway.

ECM receives a signal when 4wd is commanded then tells the ABS module of the change in driving style, if it didnt then fault codes would be stored for different wheel speeds from tire slipping.

Good Point, but 4 Wheel ABS wasn't even on the Radar in 91. At best you could get was Real Wheel ABS which worked off the differential rear carrier IIRC and not wheel sensors themselves. Also I think the Rear ABS was only OPTIONAL on the 88 New Body Style, not Squares. By 92, Rear Wheel ABS was required and then standard equipment. Again that's IIRC, it was 96 when they went 4 wheel ABS on the GM trucks. I think he's OK on that issue in this case.