91 Suburban Issues

[jbclassix]

So this is mostly going to be a parts truck for my 1970 build, but While I am working on the 70 body, we are driving this truck. I traded my wheels and tires off my 70 for this rig. It is a 1991 V2500 bare bones 4x4. It had a SES light on when I bought it, and a few other problems that were easy to fix. I have a 43 code that is active right now. I reset it and it came back. I checked the knock sensor and it is new, and ohms are within range, so I moved on to the esc... ok... where is the esc! I have a 95 Yukon and it is mounted on the top side of the bracket that the EGR sol. is mounted to. On the 91 there is not even a connector in that location as indicated by "C"

Other questions... I didn't know they started using the round style 3-pin connectors on TPS see "B" thats a yellow "B" if you cant see it

I also have a mystery relay on the fire wall see "A"



95 Yukon ESC



Also, did all 4x4's have these spacers in the X-member or only HD sprung trucks.

[rcbildr]

Those spacers are stock, but in the stock location. I've heard about that being done to improve rear driveshaft angle after installing a lift. Usually the crossmember is flush to the frame the the spacers go between the bolt head and the frame on the inside...my 85 3/4ton was that way. Sorry I can't help with the other questions...I've only really worked on diesel burbs.

[Jonboy]

The mystery relay is the fuel pump relay. The wire colors are the same as the earlier TPS; I'll be finding out pretty quickly if is is a direct swap. I am putting a 91 engine in a 87 truck. I don't know if there is a seperate ESC module; it may be in the computer. You may also want to check your wiring to the knock sensor also.

[JEM]

Originally Posted by Jonboy

The mystery relay is the fuel pump relay. The wire colors are the same as the earlier TPS; I'll be finding out pretty quickly if is is a direct swap. I am putting a 91 engine in a 87 truck. I don't know if there is a seperate ESC module; it may be in the computer. You may also want to check your wiring to the knock sensor also.

My '91 TBI 454 does not have a separate ESC module.

[jbclassix]

So I looked at a '90 Blazer with a 350/700R-4 and it was in the same location as the '95 Yukon with a 350/NV3500, so maybe it is not separate on 3/4T and 1T models... anyone?

[jbclassix]

Update on where I am at and what issues the truck is having now.

SES code 43- turned out that the computer was the wrong one for the truck. Replaced the computer and had no further issues with this code.

I was averaging 10.0mpg and running at 210-220 degrees F- rebuilt TBI unit, installed new o2 sensor, and installed 160deg t-stat. I am now averaging 13.3mpg. With light driving or hwy driving I would run at 160-180 degrees, but city driving or climbing a hill it would climb to 210-215 degrees. I found that the fan clutch was leaking fluid, so I borrowed the '02 fan and new clutch off my 95 Yukon... no change. This concerns me because my Yukon would do the SAME thing and just died about a week ago. I cant loose another engine at this point. Any thoughts?

[Skratch]

Just a thought, but if you're climbing in OD then the tranny is heating up way hot and the factory cooler integrated into the radiator doesn't help.
On my 4x4 we installed a 4 core radiator first, still got kinda hot, so I plumbed in a secondary cooler inline with the factory cooler that is in the radiator . . . now the truck runs much cooler pulling or climbing hills. I installed the cooler coming out of the tranny and then flowing into the factory unit to avoid overcooling in the winter.
I thought all along it was my engine, turned out to be the tranny all along that was really overheating.

[joe231]

Does it have a fan shroud?

[jbclassix]

Originally Posted by Skratch

Just a thought, but if you're climbing in OD then the tranny is heating up way hot and the factory cooler integrated into the radiator doesn't help.
On my 4x4 we installed a 4 core radiator first, still got kinda hot, so I plumbed in a secondary cooler inline with the factory cooler that is in the radiator . . . now the truck runs much cooler pulling or climbing hills. I installed the cooler coming out of the tranny and then flowing into the factory unit to avoid overcooling in the winter.
I thought all along it was my engine, turned out to be the tranny all along that was really overheating.

Once I get my 4-core cleaned out I am going to install that... The engine oil cooler is remote, but the tranny cooler is integral. I definitly plan on nstalling a remote tranny cooler and tranny temp gauge since I am going to be towing a lot. The Yukon on the other hand has in integral engine oil cooler, and manual tranny. But it only had a 2 core radiator. I think you are right on with the tranny causing the temp to go up on the Suburban.

Originally Posted by joe231

Does it have a fan shroud?

Yes, they both did.

[Skratch]

It took me two trannys and several years to finally get it right myself.
The extra cooler really makes a big difference and the gauge is handy too.

Both of my Burbs had the external oil cooler from the factory, but neither had an external tranny cooler even though they both have the RPO code for the tow package . . .

[jbclassix]

Originally Posted by Skratch

It took me two trannys and several years to finally get it right myself.
The extra cooler really makes a big difference and the gauge is handy too.

Both of my Burbs had the external oil cooler from the factory, but neither had an external tranny cooler even though they both have the RPO code for the tow package . . .

I hope I don't loose a tranny! The burb has a 4L80E, which is one of the main reasons I got the truck! My old 96 K2500 (can be seen in my 70 burb post) had a 4L80E and external cooler, and I abused that tranny till the day I sold it... at 212K miles! Never had one problem!

[jbclassix]

So i was wondering if anyone had any pictures of 73-91 burbs with a factory remote transmission cooler. I have noticed that my tranny likes to downshift and/or run the TC unlocked more than it should. I am going to troubleshoot the TPS and see where that leads me... but I wanted to see if GM offered a remote tranny cooler of any kind for these bodies. Maybe a 91 diesel? I have 2 aftermarket coolers, but I am not a big fan of rubber hoses with worm-drive hose clamps.

[maynardtruckin]

Originally Posted by Skratch

Just a thought, but if you're climbing in OD then the tranny is heating up way hot and the factory cooler integrated into the radiator doesn't help.
On my 4x4 we installed a 4 core radiator first, still got kinda hot, so I plumbed in a secondary cooler inline with the factory cooler that is in the radiator . . . now the truck runs much cooler pulling or climbing hills. I installed the cooler coming out of the tranny and then flowing into the factory unit to avoid overcooling in the winter.
I thought all along it was my engine, turned out to be the tranny all along that was really overheating.

There is no such thing as over cooling a automatic!