--------------------------------------------------------------------------------

i just bought a 94 suburban k2500 with the auto trans. i bought the truck for 225$ and when i test drove it, it was fine shifted solid all gears fine. then on the 40mile drive home i have 1st 2nd and 3rd but no 4th lift off the gas and rmp would drop to 1k. then it would feel like you had no gears until it grabed at the speed you were going. and it didnt help that i had 30miles to go running 45mph at 3500rmp most of the way. got it home droped it to second atg 20mph heard it click but no rpm spike and the same for 1st. this is my first truck like this and im just looking for some oppions.

thanks guys

also gotta do all the fluid changes today oil, trans, transfer case and rear end. and check the harmonic balancer because it has a bad vibration at idel.

it has 220k miles on it, no dash lights stay on, and the shop wants 90 buck to scan her. so im goin to try and unplug each sensor on the trans one by one and drive it after each to see if that helps or hurts it. is this a bad idea or should i waste the 90 buck on a scanner?

 

All your gauges work?

 

yes they do. however all of me battery cables where loose and a ground wasnt connected havent been able to drive it yet to see if the problems fixed...

 

Grounds and Speed sensors on the Transmission are two things to really check on these. I had to replace both the input an output speed sensors on the transmission this weekend. Went from shifting rough and going in to limp home mode, to shifting like a new transmission.

Another thing to do is to check the Coolant Temp sensor at the front of the engine, mine was fine but the connector was bad. Also made a big impact. For the record, this sensor isn't the one that reports temperature to the gauges, as my temp gauge work just fine.

 

Short out the A and B terminals and read the codes yourself 1 flash and then 2 flashes mean system is working it will do this 3 times the it will flash random codes have pen and paper to keep track the if you google say a code 35 it will point you in the right direction see below picture for terminal location

 

to mayhem, I agree step one, don't pay 90$ for something a paperclip can do. Also look under the hood, does it have a throttle cable by chance?

 

Ahem Mayhem you get my permission to borrow that picture it's ok us 6.2/6.5 guys gotta stick together to get the help where we find it.


FYI gous this only works for OBD-I trucks pre 96 vintage, OBD-II requires a reader but most part stores will read codes for free on the OBD-IIs