overdrive

**luciangage** · 10-09-2006, 06:45 PM

i have a 94 z auto. i bought the car a few weeks ago and it had no overdrive. ireplaced it w/ a used one but it was no good. i decided to let my freind rebuild the one that was in the car. he is going to school for mechanics and is doing it there. i bought the kit from tci that has the exact same parts as their street fighter kit we put it back in and a shift kit. car shifts hard in a good way but still will not go into overdrive. this is my first trans experience so any ideas will be greatly appericiated

**performabuilt** · 10-09-2006, 06:55 PM

Im assuming you have a 1994 z28 ?
Ok in the 4l60e there could be several reasons for no fourth , First get it scanned for codes and then let everyone know what they are .
performabuilt

**luciangage** · 10-10-2006, 04:36 PM

it is a z28.2 codes#59 trans temp. circut high and #90 tcc enable fault(qdm) thanks

**performabuilt** · 10-10-2006, 07:42 PM

trannsmission will not go into overdrive as long as those codes are there either will put it in hot mode and disallow od ,Also are you sure its a 94 trans?
performabuilt

**luciangage** · 10-11-2006, 05:23 PM

what causes these codes? sensors? how do you test? do i need a trans range pressure switch assembly? pressure control solenoid? what causes hot mode is there a solenoid for od? i vve got no idea about this stuff. im trying to learn thanks for being helpful and responsive

**luciangage** · 10-11-2006, 05:24 PM

oh yeah car had reman trans in it when i bought it so car is 94 trans ??? it this a factor?

**performabuilt** · 10-11-2006, 05:30 PM

Well the codes could be real codes caused but overheating due to tcc not locking , Or they could be ghost codes from a bad trans range presure switch , thats the hard part determining which , A technicial with a good scanner could easily make that determination by reading the data stream to see whats actually happening , If i was gonna guess though I would go with range presure switch ,
performabuilt

**luciangage** · 10-11-2006, 05:48 PM

so go ahead and replace it?

**luciangage** · 10-12-2006, 04:26 PM

ok that didn't work so now what?

**performabuilt** · 10-13-2006, 06:34 PM

wait a minute I just remembered something I ran into a couple years ago , We had a 1994 z28 come to the shop to have the unit replaced , So we replaced it with a unit built non pwm for a 1994 after we built it we had no fourth a quad driver failure and a trans temp sensor lockup code, just like yours ,
The solution was to put the original transmissions internal wiring harness and solinods on it .After doing some research I learned a couple , under the dash we found there was not only a gm1 plug but and obd2 as well though it gave the obd1 gm1 code numbers and the obd2 plug didnt work ,
to make the tranny work we had to use the wiring harness and solinods specifically the pwm solinoid from a 1995 year , Is there a prndle switch mounted to side of transmission where the linkage goes , black thing with two plugs on it ?
performabuilt

**luciangage** · 10-15-2006, 09:33 AM

no i dont have that plug and i dont have the original wiring either. however i do have the motor and trans out of a 94 caddy. this is what i was going to build for my car. i could use the wiring harness, solenoids, and computer on my car? iwould have to use lt1 edit or something but if you think it might work i can try it. thanks. oh yeah i bought an atsg manual so maybe this will help