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87renix
October 29th, 2017, 13:33
So the short story is my transmission is a 95 and it won't shift out of first gear without letting off after hitting 3k rpm until its warm. And if its really cold it won't shift out of first at all. My solenoids ohm at 11-12 cold across the board so I think those are ok. I've been trying to find a way to test the output sensor on the transmission since its somewhat pricey and either have to pull one from the junkyard or order it online. I'm not sure if that would even be the problem since it shifts great once it has some temp to it. Anybody have any experience with this? I might try and talk to one of the transmission shops in town and see what they think.

lawsoncl
October 29th, 2017, 14:22
Start by checking the throttle body to tranny shift cable for proper adjustment and fluid level. Bad solenoids usually stop working when they get hot. The rear output speed sensor generally either works or it doesn't, typically they also fail when hot. It could also be a TPS sensor issue, and sounds like you have a meter you can use to test that.

You could also pull the trans fuse and see if it shifts correctly manually to eliminate the solenoids and electronics.

87renix
October 29th, 2017, 20:12
Shifts manually just fine, fluid level I've been messing with for a bit. Just put the trans in so haven't gotten it prefect yet. This trans was in a buddy's jeep and did the same thing but we figured it was due to not having the input sensor since his is a 98. Tps is new, doesn't mean much but I don't think that would do it. Since its done it on two different jeeps with two different tcms I think it's something on/in the trans. Just hoping its not the clutch packs going out

lawsoncl
October 29th, 2017, 21:01
The rear sensor on the 95 outputs pulses as the magnet swings by the sensor. The amplitude of the voltage spike is proportional to the rpm. I measured it reaching 35-volt peaks around 60mph, and down as low as a few volts at real slow speeds (where the tcu isn't going to try shifting anyway). I was using an o-scope, but a basic meter should show something using the ac voltage setting. You could try measuring at the TCU in the driveway with the xfer case in neutral.

It sounds like maybe something is sludged up in the valve body, and perhaps one of the high quality cleanup additives will help?

cruiser54
October 30th, 2017, 06:56
How about going to www.cruiser54.com and doing tips 1 through 5.

Also Tip 10.

Then test the trans side of your TPS using Tip 8.

87renix
October 30th, 2017, 09:20
The trans has all new fluid basically so while its still a little low I'm gonna add a good additive to it. I have a bad feeling about it but the trans was free so it's not the end of the world if it only last a few months lol. Ill see if I can get a reading with the tc in neutral with my meter as well

cruiser54
October 30th, 2017, 14:05
The trans has all new fluid basically so while its still a little low I'm gonna add a good additive to it. I have a bad feeling about it but the trans was free so it's not the end of the world if it only last a few months lol. Ill see if I can get a reading with the tc in neutral with my meter as well

I think you're barking up the wrong tree, especially if you don't look at my Tips. From Tip 1:

The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, failed emission tests, and wasted money replacing components unnecessarily.

All the components listed below ground at the dipstick tube stud:

Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition Control Module, Fuel Injectors, ECU main ground (which other engine sensors ground through, including the Oxygen sensor, Knock Sensor, Cruise Control and Transmission Sync signal. All extremely important stuff.

The factory was aware of the issues with this ground point and addressed it by suggesting the following:

Ecomike
October 30th, 2017, 14:58
While you are working on the speed sensor issue angle, try a pint of Trans-X additive to see it does not fix it. It will dissolve any varnish that is making the valves in the valve body stick when cold.


Cruiser54, this is a 95, not an 87 from what he said in his first post.

OP, is the entire jeep 95 or 87-95 hybrid? If it is both, what are using for a TPS, TCU, and sensors year wise?


Shifts manually just fine, fluid level I've been messing with for a bit. Just put the trans in so haven't gotten it prefect yet. This trans was in a buddy's jeep and did the same thing but we figured it was due to not having the input sensor since his is a 98. Tps is new, doesn't mean much but I don't think that would do it. Since its done it on two different jeeps with two different tcms I think it's something on/in the trans. Just hoping its not the clutch packs going out

87renix
October 30th, 2017, 22:44
Ecomike, thats where things get interesting lol, its a 95 trans that I put in my 87 that was originally a manual with an ax15. TCM and all sensors are from renix era and I added the tcm and wiring out of a renix jeep from the junkyard.

Crusier54 I know it is not external from the transmission because it has done the same thing in two different jeeps with different electronics.

I would think it would have to do with the tcm harness that I added but it shifts perfect when warm and because this is the second jeep it has done it in. I have a feeling its a mechanical issue inside the transmission but trying to eliminate any other possibility.

cruiser54
October 30th, 2017, 22:44
While you are working on the speed sensor issue angle, try a pint of Trans-X additive to see it does not fix it. It will dissolve any varnish that is making the valves in the valve body stick when cold.


Cruiser54, this is a 95, not an 87 from what he said in his first post.

OP, is the entire jeep 95 or 87-95 hybrid? If it is both, what are using for a TPS, TCU, and sensors year wise?


we don't know for sure. Either way, the TCU ground is at the dipstick tube......

lawsoncl
October 31st, 2017, 10:04
we don't know for sure. Either way, the TCU ground is at the dipstick tube......


Very true, fixing that can only help. I was shocked when I saw that crappy crimp - no solder or barrel just the wires pressed together. It shifting fine manually with the TCU fuse pulled does point to something on the electronics side. Worst case, swap the shift solenoids and see if the problem changes to starting in 3rd gear instead of being stuck in 1st when cold.

Ecomike
October 31st, 2017, 10:13
Just to be clear, is it shifting electronically (not asking about manual shifting), properly when warm and not when cold?

If that is the case, I would start with adding a pint of trans-X for sure. Been using it for 44 years now. Awesome product, and totally safe. Drain a little fluid if needed first, if it is 100% full to the mark.

Then go from there with the other checks to look for a temp sensitive electrical connection or solenoid. But my money is on varnish making the solenoids or valve body valves stick until the fluid is hot. Trans-X does wonders for that.

Ecomike, thats where things get interesting lol, its a 95 trans that I put in my 87 that was originally a manual with an ax15. TCM and all sensors are from renix era and I added the tcm and wiring out of a renix jeep from the junkyard.

Crusier54 I know it is not external from the transmission because it has done the same thing in two different jeeps with different electronics.

I would think it would have to do with the tcm harness that I added but it shifts perfect when warm and because this is the second jeep it has done it in. I have a feeling its a mechanical issue inside the transmission but trying to eliminate any other possibility.

ParadiseXJ
October 31st, 2017, 21:38
Is the TCM (TCU) harness connector AND the TCM connector itself the same color? My truck (88) ran fine with a 94 AW4 TCM, until I checked the Renix TPS to adjust it, because I was having weird shifting problems. I got 0 signal at the TPS. So I pulled a junkyard TCM and it's matching engine side harness. Problem gone. I had to pour over wiring diagrams until the light bulb in my head went on.

Anyhoo, if the harness connector and the TCM connector are NOT the same color then they're mismatched. This sounds very familiar.

cruiser54
November 1st, 2017, 00:13
Is the TCM (TCU) harness connector AND the TCM connector itself the same color? My truck (88) ran fine with a 94 AW4 TCM, until I checked the Renix TPS to adjust it, because I was having weird shifting problems. I got 0 signal at the TPS. So I pulled a junkyard TCM and it's matching engine side harness. Problem gone. I had to pour over wiring diagrams until the light bulb in my head went on.

Anyhoo, if the harness connector and the TCM connector are NOT the same color then they're mismatched. This sounds very familiar.

Yup.These guys are on a rabbit trail.

90xj06
November 2nd, 2017, 11:19
if your losing the tps signal to the tcu it will get stuck in 1st gear. sounds like it could be a bad connection cold and gets a good enough signal when hot.

lawsoncl
November 3rd, 2017, 14:02
if your losing the tps signal to the tcu it will get stuck in 1st gear. sounds like it could be a bad connection cold and gets a good enough signal when hot.


Good point. He did say a 89 TCU. Did you add the dual-output TPS sensor, or just splice into the existing single output fro the manual setup? The two outputs run opposite, voltage-wise, so feeding the TPS signal meant for the engine computer to a renix era TCU will not work well (it will think you're at wide open throttle when you're really at idle).

Ecomike
November 3rd, 2017, 14:09
Heat up the output sensor on a cold morning start up with a hair dryer?

Then pour cold ice water on it to if either matters.

So the short story is my transmission is a 95 and it won't shift out of first gear without letting off after hitting 3k rpm until its warm. And if its really cold it won't shift out of first at all. My solenoids ohm at 11-12 cold across the board so I think those are ok. I've been trying to find a way to test the output sensor on the transmission since its somewhat pricey and either have to pull one from the junkyard or order it online. I'm not sure if that would even be the problem since it shifts great once it has some temp to it. Anybody have any experience with this? I might try and talk to one of the transmission shops in town and see what they think.

Ecomike
November 3rd, 2017, 14:12
Good points but on post #9 he says:

TCM and all sensors are from renix era and I added the tcm and wiring out of a renix jeep from the junkyard.

I'd test the TPS sensor signal at the TCU.


Good point. He did say a 89 TCU. Did you add the dual-output TPS sensor, or just splice into the existing single output fro the manual setup? The two outputs run opposite, voltage-wise, so feeding the TPS signal meant for the engine computer to a renix era TCU will not work well (it will think you're at wide open throttle when you're really at idle).

87renix
November 4th, 2017, 13:23
it has the dual plug tps for the auto on it and wired correctly. It shifts perfect at temp just not first thing in the morning or if its cold. Haven't messed with in a few days because I've been busy and haven't been driving it. Hopefully will get out there this week again and start messing with it more. Probably gonna pick up a bottle of transX as I have heard a lot of good things about it. Might try heating up the sensor like ecomike said.

Ecomike
November 4th, 2017, 19:38
I have fixed your exact problem on many Renix Aw4s, a GM, Dodges and Fords over the last 45 years. If it works, do second transfusion about 200 miles later, and add the Trans-x again. You need to slowly get the dissolved varnish out. Dissolve then drain and dilute it, I usually do it 3 times, with 3 Qts at a time of Tranny fluid drained and added.

it has the dual plug tps for the auto on it and wired correctly. It shifts perfect at temp just not first thing in the morning or if its cold. Haven't messed with in a few days because I've been busy and haven't been driving it. Hopefully will get out there this week again and start messing with it more. Probably gonna pick up a bottle of transX as I have heard a lot of good things about it. Might try heating up the sensor like ecomike said.