Even more overdrive problems

[EarlKann]

Alright guys, I am quickly reaching the end of my rope here. When I first got the crew conversion running it seemed fine, but then about two weeks ago it started with the dropping out of overdrive on the freeway. Since then I have searched the board and tried everything that I could find related to this problem. Here is the rundown of what I’ve done so far.



Adjusted the TPS. Initial check found the voltage a bit low 0. 55@idle. I adjusted it up to 0. 65 and test drove [no change] and again up to 0. 96 The shift rpm’s seemed better but still dropped out of overdrive. Went to a friends and swapped out the TPS for another one off of one of his trucks [one that I know works] Installed at 0. 68V at idle and test drove, no change again. Both TPS sensors were reading above 3. 2V at WOT when adjusted to 0. 6X at idle, so I re-adjusted to 0. 36V at idle in order to get the WOT reading down to about 2. 76V, still no change [this is the current setting still].



Replaced the VSS. This seemed to fix the bouncy speedometer problem I was also having, but in the process I broke the little gear ratio adapter thingy so now my speedo reads slower than the actual speed.



Cleaned and greased every electrical connector that I could find with electrical contact cleaner and dielectric grease. Even fooled with most of the connectors to make them a bit tighter where I could. Cleaning the connector at the trans temp switch seemed to make a difference for about 20-minutes, then it came back. Went ahead and replaced the Trans Temp Switch, still no change.



Dropped the trans pan and inspected for loose bolts/damage/etc. Found nothing, replaced trans filter and fluid.



Spliced in a toggle switch to ground in the overdrive solenoid wiring. Flipping the switch while driving engages the overdrive and eliminates the problem, otherwise it still happens, so it must be something electrical…right??



At this point I am a bit frustrated with the whole thing so I have walked away and left it sitting in the driveway for a few days while I cool off.



There are a couple of things that I have though of that could be wrong, but I don’t know if they would be related to this. #1, when I put the truck together I adjusted the TV cable the way I thought that it should go [found on here 0. 18 gap]. But I don’t have a factory service manual so I wonder if I did this right. Anyone have the correct procedure for adjusting the TV cable that they would care to post??



Also, #2, the 10amp fuse for the dash lights is blown, and blows immediately if you try to install a new one. Don’t know the reason for this or if it could be related to the OD problem.



Any suggestions are appreciated. I intend to keep working at figuring it out myself, but I’d also like to know if anyone knows of any shops in or near the SoCal inland empire area [Riverside / San Bernardino] that are good. I don’t want to go to Bellflower, and I don’t want to deal with someplace that will say “you need a new TPS” only to find out $200 later that the TPS wasn’t the problem.



Thanks in advance,



Donald

 

[EarlKann]

Have I stumped everybody, or is it just to long to read? :-laf

 

[paccool]

Hey Donald, glad to hear you are getting the truck on the road.



Sounds like you have tried most of the "usual" stuff but it sure sounds like the TPS symptoms I had. The truck would shift out of OD when going down the road at 65 or 50 or where ever. Cleaned the contacts and it was OK for a few months then did it again. I finally got tired of fighting this and took the TPS out of the circut completely. I replaced it with a potentiometer mounted on the dash and I can adjust this to the shift point that works best if I'm empty or towing the travel trailer or flatbed. I use the OD switch a lot when towing and this setup works great for me! It shifts right now at 45 MPH and downshifts at the same point. Before it seemed to just freewheel when slowing down but now I can feel it shift down when coming off the freeway or coming to a light.



I got the instructions from another member in Arizona who did this to his second gen. I will try to get this together tonight and post it. I asked the member I got it from if he minded if I post it and he said no. He didn't post it because he said it seemed there were always someone that said you shouldn't do this or that he got tired of hearing it. This is one of those things that works for me and I like it but others may not. If it can help, use it. If you don't want to use then don't. It is easy to install.



I'll also try to find the procedure for the TV cable if yu still need them. Pretty sure that is in the manual.

 

[JFaughn]

Do'nt forget the bake sw. it turns off lockup & cruse, what ever I do I try to verify what ever conclutions I come up with in order not to buy extra parts. I bought my truck and when driving home I noticed that the lockup would go in & out , so I tried to pull the brake pedle up when crusing with my foot and the L. U. & C. C. would work , so when I got home I loked at the brake sw. and it was'nt adjustable like every other I've seen , so I hotglued a small washer on the foot of the sw. foot and now works fine for the last 8 mnths. if your sw. is warn more than mine than the washer will not work , you'll need a new one ,but check it out first that the turn off sig. from the the brake sw. works at the wright time.

 

[paccool]

John, the 94 models were the first ones with a lockup converter, the 93's did not have one. You are right about the brake light switch though, it can interfere with the cruise control if the switch gets pushed back out of the holder and is not closed good by the brake arm. I have had mine bounce in and out of cruise due to the switch problem. One additional thing this does is to also turn on the brake lights so there is at least an indication of a problem.



Stan

 

["Mad Max"]

Don,

What cured mine was tightening the nut, just till 'snug', under the TPS/diaphram bracket. Under the bracket, along the axis of the shaft, is a nut, 14mm I believe, that had gotten loose. I tightened it up till contact and just a bit more but not tight, and my OD never, ever gave me a problem again. So, jsut below the big bracket, under the tps and diaphram housing, along the shaft, should be a little nut, and I bet it's loose. Tighten it up the shaft till shug, and I'm beting you're there.

- Sam

 

[EarlKann]

Great, thanks for the help guys.



I was starting to think that I was all by myself here.



I'll try the brake light switch and the nut under the TPS the next chance I get.



Stan, If you have that procedure for the TV cable that would be great. I don't have a FSM and I just kinda winged it when I put it together. If I can't get it figured out I might go with the potentiometer. Is that something that you can get at Radio Shack?

 

[paccool]

The local Radio Shacks here did not have the pot. The might have it in the catalog. I got it from a used electronics parts house.



The TV cable adjustment calls for the engine to be at normal operating temp, the throttle all the way to the low idle stop and the idle adjusted to proper rpm. There is a pin in the slot on the TV cable and there is supposed to be a gap of . 180" between the back of the pin and the rear of the slot. Sounds like a straight forward adjustment. Remove the stop at the rear mount, adjust and then reinstall.



Hope this is what you needed.



Stan

 

[EarlKann]

The local Radio Shacks here did not have the pot. The might have it in the catalog. I got it from a used electronics parts house.



The TV cable adjustment calls for the engine to be at normal operating temp, the throttle all the way to the low idle stop and the idle adjusted to proper rpm. There is a pin in the slot on the TV cable and there is supposed to be a gap of . 180" between the back of the pin and the rear of the slot. Sounds like a straight forward adjustment. Remove the stop at the rear mount, adjust and then reinstall.



Hope this is what you needed.



Stan

Thanks Stan,



That's about what I did, but I don't know if the engine was at operating temp and I didn't check the rmp, It sounds fine so I never thought to check it.



Donald

 

[EarlKann]

Still having problems!

This damn overdrive still isn't working right.



So I go ahead and take the TPS and bracket off looking for this nut that Sam is talking about. The only thing that I can find is the 10mm that is used to adjust the TPS. I looked all over and didn’t see any nut. Even shoved my digital camera down there and took some pics to try to see anything underneath that I was missing.



I guess it probably doesn’t matter any more though, cause in the process of putting it back together I accidentally broke one of the electrical connectors off the TPS. #@$%!

Not wanting to spend the $$ on a new one, I went and bought the stuff to install a potentiometer as Stan described. Got everything installed and adjusted to 1. 0V per the instructions in Stan’s post. Drove around the block and it seemed to be shifting just fine. Then on the way to work this morning (first time on the freeway) it starts again with the overdrive, on/off/on/off/on/off. So I throw the toggle I installed in the OD circuit and it shifts into OD and stays there.



I’m still assuming that since my toggle override works that this has got to be an electrical problem. It cannot be the TPS at this point, cause I don’t have it connected anymore. I guess I’ll go back and check all of the connections again [trans temp, crank sensor, pcm] *** well as the ground wires. Anybody have any other suggestions?? This is really starting to get on my nerves.

 

[CLiberty]

Sure sounds like it`s either an input problem, i. e. speed sensor/brake lamps etc. , OR maybe the PCM is commanding OD but the ground signal at the solenoid is poor. You could try tapping a DVOM into that ground wire you ran and see what the PCM is doing. You should have system voltage (12. 5-14v or so) at that wire when NOT in OD. As soon as the PCM commands OD the voltage should drop to almost zero, IIRC my truck reads approx . 5v when in OD. Also ck the connector to the PCM, and the one by the intake manifold, on my truck both connectors had a small amount of white "crud".