1993 gmc 6.5 td with 4l80e

[just a number]

I think I figured out why you can't clears the codes. the '93 and earlier have the mechanical IP(DB2). I wondering if you still have a standalone controller for the transmission. you can clear it by pulling the ECM fuse for 10 seconds. mine had 2 of them. don't know what one controlled the computer. they were both 10A.

the error is "overdrive ratio". try PMing Docdray. he might have some ideas too.

any luck with the coolant light?

 

[kimagine]

I think I figured out why you can't clears the codes. the '93 and earlier have the mechanical IP(DB2). I wondering if you still have a standalone controller for the transmission. you can clear it by pulling the ECM fuse for 10 seconds. mine had 2 of them. don't know what one controlled the computer. they were both 10A.

the error is "overdrive ratio". try PMing Docdray. he might have some ideas too.

any luck with the coolant light?

Thanks for the info. Have not had a chance to mess with it yet. I'll try the fuse/s sometime this week after work.Thanks,Mark

 

[kimagine]

I think I figured out why you can't clears the codes. the '93 and earlier have the mechanical IP(DB2). I wondering if you still have a standalone controller for the transmission. you can clear it by pulling the ECM fuse for 10 seconds. mine had 2 of them. don't know what one controlled the computer. they were both 10A.

the error is "overdrive ratio". try PMing Docdray. he might have some ideas too.

any luck with the coolant light?

Small update: I pulled the fuse (just one on this truck that I saw) for about 15 seconds and then reinstalled and tried to pull codes again to no avail. Still the 68 and the truck was not even started before rechecking.:mad2:. I really need some more daylight and some warmer temps. It does make me believe there is an electrical issue there and not the tranny.

Mark

 

[bison]

disconnect the batts,if that aint clearing the code,then you might have a buggered TCM.

 

[kimagine]

disconnect the batts,if that aint clearing the code,then you might have a buggered TCM.

I was thinking the same thing. I was on another thread just discussing the same thought. If the TCM is bad, thank GOD that GMC will have to honor a warranty on the brand new $700.00 unit they just installed and said all was perfect.....

 

[bison]

I was thinking the same thing. I was on another thread just discussing the same thought. If the TCM is bad, thank GOD that GMC will have to honor a warranty on the brand new $700.00 unit they just installed and said all was perfect.....

$700!!! a replacement TCM can be had for under 175 bucks

 

[docdray]

not sure on 93 ecm, but is qdm or tcm matched to tranny?? besides the brake switch or tachometer, if this problem (code 68) started with the rebuild, I would think its a tranny component. again, unless you have a faulty TPS, I'm not familiar with 93 and back.

68 sets if slipping in fourth with tcc engaged. generally failing clutches. verify proper voltage and good ground to tranny.

you mentioned repairing the TPS wires-are you positive connections are good, batteries good and proper voltage from alt.

very unlikely its the TCM, unless its programmed wrong. verify proper voltage and ground at connector- attached pic.

Check brake switch, tachometer function, TPS, then it has to be either TCM or Tranny component-pressure switch, temp sensor, solenoid or internal problem(obviously)

 

[just a number]

never thought about the brake switch. there are 2 plugins on it. the one closer to the nut is for the lights and the second on is the tranny. it should be closed when the brakes are off. just thinking you might have a worn point in there. I know mine was. all I ended up doing was cleaning in up and turning the shaft 90* and it worked fine again.

 

[gmc junky]

which selonoid was bad..??? mine has similar problems...going to change both coolant sensors,, one on hose housing and side of block..???