1987 V2500 Choke light kicks on, and Trans wont kick into overdrive

[Auron014]

Hey all,

My dad and I just picked up a 87 GMC suburban, TBI 350, 700r4, 4x4. The only issues we've found so far (about 100 mile drive from where we bought it, back to home) is the choke light kicks on at random, which we were told would happen because there is a vacuum leak on the back of the throttle body, which we plugged before we left and it kicked on anyways. Secondly, and arguably the worse of the problems, is the trans wont kick into over drive. we were told the engine, trans, and transfer case were all rebuilt and put back in less that 30k miles ago, and it hadnt had any problems other than the vac leak causing the choke light to kick on. We checked linkages, verified we didnt have it in the wrong gear (from what I can tell, column pattern from bottom up is 1st, 2nd, Drive then into neutral), checked all the vacuum and hydraulic lines to the unit itself, and nothing seems to be out of place. The only thing we did find is that the cruise control cables arent hooked up but it dont know if that would cause it but its the only thing ive found really out of whack so to speak. Any help or tips would be greatly appreciated. Thank you!

 

[Itali83]

Sounds like you’ve got quite the Mis-mash of parts going on. There should be no “choke” light on a tbi truck. Should be a check engine light. Plus, there should be an overdrive symbol between neutral and drive. So, you’ve either just got an older cluster swapped in or other major issues. Are you sure you’ve got a 700r4 transmission?

 

[Auron014]

About the only thing im sure of is that its not on fire, all we have to work with right now is what we've been told. I know its a TBI engine, buuut yeah the choke light kicks on at random, which to me didnt make much sense but i havent had much time to wrench on it, and the Gear indicator on the dash is gone so we dont have much to work with there either.

 

[Rusty Nail]

I agree with Itali83. Pretend the light says "check engine", not "choke".
Upon reading the codes from the ALDL, I imagine you wil find code #42 , perhaps among others

gears 3 AND 4 have different detents, or positons on the column and IF what you say is true , you MAY have a th-350, not a 4 speed auto , thus tripping the light BECAUSE there MAY BE a square 4 wire plug dangling next to your transmission that is intended to lock-up the original torque convertor?

That's my guess without pictures. multi parts mish mash. mmhmm.
three speeds are not only cheaper, they are better. Consider yourself lucky?


pix or it didn't happen yo, welcome to the internet.
I wrap the plug around the shifter linkage, AS SHOWN.. good luck. All you need is a piece of electrical tape - to cover the light.
took the 4 speed out on purpose. My 1988 TBI truck has a 1986 spec transmission and dangly plug.

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[Auron014]

Thanks for the Input, I'll take a look around it today when I get off work and grab pics of what I can.

 

[gmbellew]

700r4 column pattern is P R N OD D 2 1. if you are missing a stop on the column, somebody may have put in a non-OD transmission. compare the pan shape to GM transmission pan shapes to figure it out.

if you do have a "choke" light, somebody has swapped in a different cluster. if it is the check engine light coming in, jumper A and B on the aldl port and turn the key to ON. it should flash "12" three times and then any stored codes and then "12" three times.

could be a large vac leak causing MAP sensor reading issues? EGR is also a soft code that usually doesn't cause drivability issues. also not sure how you "plug" a leak on the TBI base gasket without just putting in a new gasket. any symptoms of poor running?