OK, I know there are some GM tech's on here, so I'm asking for some help.

I recently re-built the motor in my daughter's 1993 Chev 1/2 ton 4x4. A ,couple of days later it quit shifting into high gear. Is the one with over drive.

Trans was completly re-built in the spring and has been fine up until now. I goes into 4wd ok and shifts into 2nd fine. No burnt smell to the fluid and it is nice and clean.

The tranny & torque converter were left in the truck and lost no fluid. I'm starting to think there may have been a small piece of debris that ended up in the cooler line when I hooked it back up to the rad cooler ports.

The check engine light has not come on, so I'm not sure I would be able to pull any codes.

What do you guy's think, this transmission deal is out of my league as I'm an engine guy.

The, Governor / Dan Logan

dan,
with all the money you are saving with the tire impound rule, you should have saved more than enough to buy her a new truck. quit being a cheap skate!!!!

take care
tc

Dan,

when you put the motor back in the truck did you reset the TV cable? if you did not do this there is a good possibility this might be your problem. Also check to make sure the shift linkage is adjusted properly. these will be the two easiest things to check. other than that you might have to get some one with a pressure gauge and have them hook it up to the tranny and see what the pressure levels are for each gear.

hope this helps ya.

Jerry

After I replaced the motor in my GMC truck, it did the same thing, it ended up being a TPS (thottle body positioner sensor)
replaced it and everthing was great.

TaBOGIE,

You know I did have the throttle body completly apart for a good cleaning, to include the TPS. Would I have to re-set the TPS once it was un-screwed and put back on?

Jerry,

I never unhooked the shift cables from the bracket, took the whole assembly off and left it hanging on wire from the fire wall.

Does the tranny need its own ground? I did need to replace the chassis to engine ground before it would start and come to think of it there may have been another braided ground that was bolted to the trans flange mount.

Thanks for the help so far it has got me to thinking now.

The, Governor / Dan Logan

Is it a slotted one with the wiper arm? Some have slots and some dont. (not so sure what the trucks had)

We had to hook up the computer up to set it when installing the new one. When the trans does not get a tps signal, it goes into a service mode.

I think the the ideal setting was about 35%????? (my truck is a 1993 gmc one ton diesel, auto)

DAN DOES THE SERVICE ENGINE SOON LAMP WORK? TURN THE KEY TO ON POSITION LIGHT WILL COME ON TO PROOVE OUT, THEN START TRUCK, IF LIGHT SHOULD GO OFF.

IF LIGHT WORKS BUT NOT ON THEN PROLLY NOT TPS AS IT WILL SET CODE AND TURN LAMP ON. IF LAMP IS NOT ON THEN IS MORE THAN LIKELY MECHANICAL, LIKE POSSIBLE TV CABLE ADJUSTMENT.

BUT, IF LIGHT IS NOT FUNCTIONING (I.E. BULB BURNT) THEN YOU'LL NEED A SCANNER TO SEE WHAT CODES MAY BE PRESENT.

I don't think they did % back then but it should be about .35-.50 volts maybe?? If it was %, it would be 0%.

We lost access to ALLDATA or I would look it up for you. Right now I only have access to newer stuff via GM's intranet.

Found this in the bulletins section.

Document ID# 250434
1993 Chevrolet Chevy K Pickup - 4WD


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

SERVICE MANUAL UPDATE-SEC. 7A THROTTLE POSITION SENSOR (TPS) #93-132-7A - (Mar 8, 1993)
SUBJECT: THROTTLE POSITION SENSOR (TPS) REPLACEMENT

MODEL and YEAR: 1992-93 C/K TRUCKS WITH 4L80-E AUTOMATIC TRANSMISSION

The following represents revised information for Section 7A in the 1992 and 1993 C/K Models Service Manual.

This supplements the information found under "Throttle Position Sensor (TPS) Replacement" on page 7A2-86 of the 1992 C/K Models Service Manual and page 7A17A-96 of the 1993 C/K Models Service Manual.

IMPORTANT: On all gasoline V-8 engines, the throttle position sensor is non-adjustable without retainers. In addition, on the 7.4L (V- engines, the (TP Sensor) has a horizontal electrical connector. On all other gasoline engines, the connector is vertical. For diesel engine (TP Sensor). Refer to SECTION 6C2.




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NO 3-4 UPSHIFTING (DISCONNECT CRUISE CONTROL SWITCH TO PCM #93-256-7A - (Jun 28, 1993)
Subject: NO 3-4 UPSHIFT (DISCONNECT THE CRUISE CONTROL SWITCH TO THE PCM)

Model and Year: 1993 C/K TRUCKS AND G VANS WITH 6.2L DIESEL ENGINE

CONDITION:

--------- Some 1993 vehicles equipped with the HYDRA-MATIC 4L60-E transmission and 6.2 liter diesel engine may not obtain 4th gear when cruise control is engaged and vehicle speed is above 63 mph. If the vehicle is in 4th gear at highway speeds with cruise control on and the transmission downshifts when going up a hill or if the driver manually downshifts to drive and then back to overdrive, the transmission may not return to 4th gear.

CAUSE:

----- If the vehicle is at highway speeds with cruise control on, and a 4-3 downshift is forced due to increased road grade. The vehicle then returns to stable or level road grade, a 3- 4 upshift may not occur, due to the throttle position.

CORRECTION:

---------- To improve the 3-4 upshift condition, the white wire (85) from the cruise control switch to the PCM (B10) must be disconnected.

NOTE: The PCM uses this signal to represent the status of the cruise control. The PCM uses this information to modify the shift schedules and TCC schedules when cruise has been requested. If the white wire (85) is disconnected, the vehicle may exhibit a busy condition with TCC.

Dan,reread your post,does it only shift into 2nd with no 3rd and 4th or just no overdrive?
Tim

Tim,

When it shifts out of 2nd it free revs, and won't engage again until RPM comes back down.

I even tried it in and out of 4WD as I was not sure that would matter, but no change.

I will have to look for the check engine light tomorrow, as I don't recall seeing it on.

Dan

"When it shifts out of 2nd it free revs, and won't engage again until RPM comes back down."


HMMM, STARTING TO SOUND MORE LIKE INTERNAL TRANS CONCERN, NOT ALOT OF ELECTRONICS ON THAT AGE OF UNIT. MAYBE SEE IF THAT SES LAMP WORKS AND IS OR NOT ON. IF LAMP WORKS BUT NOT ON I'D SAY IT IS PROLLY INTERNAL ISSUE.

That trans has a large weather pac type of plug into the trans, must be 8-10 wire in the loom.

The plug has to be 1 1/4 in Dia, plus there are 2 or 3 other elec plug into the trans.

Dan

YEA BUT THATS STILL A PRETTY SIMPLE UNIT BY TODAYS STANDARDS.

Well I replaced the Oxy sensor and TPS, they most likley needed it anyhow as the thing has almost 190,000 miles on it.

Still won't shift into any higher than 2nd. The check engine light was on and is now off.

What steps does it take to re-set the trans cable, even though I didn't have it un-hooked I will try any thing at this point.

Next thing to try will be the speed sensor at the trans, but that was replaced when the unit was rebuilt, but it could have gone bad I guess.

Anymore tips would be appreciated. I just don't have time or the money to pull the trans again.

I will be getting a buddy's scaner tomorrow and try, but w/o the check engine light on, not sure it will pull any codes.

Dan

make sure all your ground are hooked up when you put the engine back in

I doubt that is it if it won't up-shift past 2nd. The cable would make it shift early or late. You may have pinched a wire to the trans during the re-installation. Should have a code for that though I would think.

Back then, codes set the Check Engine Light when the problem was there and turned it off when the problem was gone. 96 and newer keeps the light on longer.

FIGURE IT OUT YET DAN?

Make sure that the torque converter did not slip uot of the pump,if the trans was at a downword angle with engine out very possible.Any leak'sbehind the converter?If that has a shift cable on it I beleive it is still a 700r4 not a 4l60.The "60's" were all electronic to my knowledge,doesn't sound electronic to me.

Was not able to work on last night, had to be out of town for a meeting.

Now have the scanner and will take a look tonite or tomorow.

No leaks at the converter, made sure it was seated into pump before motor went back in.

That was also my first thought, but low & 2nd are fine.

I'll let you know when I can find the issue.

Dan

Dan,

Once you scan for codes, you'll likely have a clue as to where the problem is.

I'm not a GM person, but I do know that your transmission will default to 2nd gear when it detects certain electrical and/or mechanical transmission problems.

The trans is controlled electronically by the PCM. The PCM activates shift solenoids in the transmission to make each shift. If it worked fine prior to pulling the engine, then my guess is that you may have a simple electrical problem that you've created somewhere.

On the other hand, why was the engine pulled? Is it possible that the transmission failed mechanically causing it to free-wheel in the higher gears and your daughter subsequently over-revving the engine?

-Maurice

Nope, intake leak letting anti-freeze into crank case. The valve covers were so full of jelly, that the only route for oil return was the push rod area.

Luckly the crank etc, checked out fine, but heads needed a major re-work. Good cleaning, hone, rings, rods and mains, new cam & lifters and it runs great now.

Dan

If you drove it with a misadjusted cable for 6 months you should just take it apart and see what is wrong. It will shift strange and you will have to let off the throttle and wait for it to hook up in third gear,this will last a while till it won't shift at all into third. Old problem and I can't remember what fixed them. Wrong pressures at wrong times.