Two questions: Instrument Cluster and AW4 shifting

I bought a '96 XJ Sport with the AW4. Two weeks ago. When I bought it I was told that the TCM was bad on it and needed to be replaced. The tranny does not shift into 1st or 2nd without sliding the lever into position 1/2 and then will not do the 1-2 upshift until about 4800 RPM. I have gone through the diagnostic notes, "Shift Pointers" detailing troubleshooting the TCM. Can't remember now which port tested bad but indeed it did test bad. So I ordered a replacement TCM off of EBay, which came in today. But while I was waiting for the new unit to come in I installed the switches as detailed elsewhere on and several other forums to lock in 1st and 2nd gear. The switches work flawlessly, giving sort of a "manu-matic transmission" so I know that my shifting problems are not related to the tranny solenoids themselves.
So after all of that, did I just get a bad TCM from the EBay dealer or could my problem be elsewhere?
Second question I think is a little easier, over the last week the tach began "sticking" it would only read between 1750-2400 RPMs. When the problem first came on I could "unstick" it and it would work perfectly again for a few days by running the truck to redline and allowing it to shift on it's own. Now the needle likes it's home. When the truck is off the needle rests perfectly at 0, but at idle it sits at 1750. The truck is quite obviously not idling that high so do I just have a stuck needle that can be lubed by removing the cluster or do I need to look elsewhere.
Wish I had more time to work on this but I am leaving for Iraq this weekend for a year, so any assistance would be greatly appreciated.
Thanks in advance

I have a tcm you can have if you pay shipping. It came from a 90 4.0. Stay safe in that mess and thanks for serving. PM me if you want that you wont get it b4 you leave but it will be there when you get back.

Oops I just noticed you have a 96. I don't know if that will work for you. If anyone wants it PM me,I don't want to toss it if someone can use it.

When the shifter is in 1-2, it won't shift from 1st to 2nd until almost at redline so that part sounds normal. The first problem with 1st and 2nd not working when the shifter in D is a real problem though. Did the replacement TCU fix it?

Solenoids can be tested by driving the car. If the gears engage, then they are working.

It would be very helpful if you posted the results you got after following through the Shift Pointers document. There could be a variety of things going on that's causing this problem, it could be as simple as a bad TPS.

To be clear, the AW4 (tranny) is electronically shifted. This means when everything is functioning properly, the solenoids shift the transmission.

When there is something wrong (TCM not getting power, solenoids dead, fried wiring) your tranny will default to 4th gear in "D". Now, you can still manually change gears by moving the gear shifter from '1-2' to 3 to 4.

The reason this works is because your gear shifter is mechanically linked to your transmission via linkages. So, just because your gears are engaging as you move the gear shifter, does not mean your solenoids are ok.

You have to test them 1) at the TCM harness 2) at the connecter in the engine bay at the firewall 3) directly at the transmission.

Here is my on-going thread with my shifting issues: http://www.naxja.org/forum/showthread.php?t=969215

eta: AFAIK, bad TCMs are fairly rare. Bad solenoids are less rare.

The upshift from 1st to 2nd in the 1-2 position is TCU controlled. It would not upshift if the TCU and/or solenoids were completely fried.

ehall said:

The upshift from 1st to 2nd in the 1-2 position is TCU controlled. It would not upshift if the TCU and/or solenoids were completely fried.

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Is the downshift from 4 to 3 controlled by solenoids too (with TCM plugged in)?

At any rate, we still need the results from the troubleshoot via Shift Pointers.

Easiest test I know of is put it in 3rd and see if it goes through 1st, 2nd, 3rd and 3rd w/ lockup (feels like 4th). You can test the lockup solenoid by letting it go into 3rd lockup and then lightly tapping the brakes with your left foot while you staying on the gas with your right foot--you should feel lockup disengage and reengage when you do this, like you are tapping a clutch pedal. If that all works as normal the solenoids are working under TCU control.

Still need to check the resistance of the solenoid circuit though. Could be wacky wiring.

bigalpha said:

You have to test them 1) at the TCM harness 2) at the connecter in the engine bay at the firewall 3) directly at the transmission.

Click to expand...

If the shifter is in 3 or OD, then the truck will not shift into 1st or 2nd at all. I will run the tests again from shift pointers and post the results this evening.
The new TCM did not fix the problem. The only difference that I can see between the modules other than serial number is original has "95L" on the label and the new one reads "96F". The truck was manufactured in Jan of 96 so don't know if the original unit is from a 95 model. Appreciate the help.

Does your tranny downshift from 4th to 3rd if you gun it in 4th? Mine does with the TCM hooked up, and does not with the TCM not hooked up.

The two computers should not be any different, as long as the connector plugs up. For the record, a 97+ will NOT fit your 96.

With those Shift Pointers results, we can narrow down the gremlin even more.

OK so maybe I didn't check the pins as well as I thought... Kinda feel like an idiot right now...
LEAD Standard Value Received Value
GRD/C3 5-8v Umm.... Where'd the wire go?
GRD/C8 Batt Voltage 11.56v
GRD/C9 Batt Voltage 11.56v
GRD/C10 0v / Batt Volt 0v / 11.56

Here's where it gets screwy. The were all tested unplugged as instructed.
D7/C14 11-15 ohms 0.6 ohm
D7/C15 11-15 ohms 14.4 ohms
D7/C16 11-15 ohms falls quickly from about 12 ohms

Reconnected connector:
GRD/D1 5v 4.79v
GRD/D2 4.5v (closed)/ 0.5v (WOT) 0.514v / 3.52v
GRD/D3 less than 0.1v .158v
GRD/D14 Batt Voltage 11.56v
GRD/D16 Batt Voltage / 0v 11.55v / 0v

armymedic said:

OK so maybe I didn't check the pins as well as I thought... Kinda feel like an idiot right now...
LEAD Standard Value Received Value
GRD/C3 5-8v Umm.... Where'd the wire go? THERE ARE NO WIRES CONNECTED IN C3? IF NOT, THAT'S DEFINITELY A PROBLEM!
GRD/C8 Batt Voltage 11.56v
GRD/C9 Batt Voltage 11.56v
GRD/C10 0v / Batt Volt 0v / 11.56

Here's where it gets screwy. The were all tested unplugged as instructed.
D7/C14 11-15 ohms 0.6 ohm TOO LOW (OBVIOUSLY)
D7/C15 11-15 ohms 14.4 ohms WITHIN SPECS
D7/C16 11-15 ohms falls quickly from about 12 ohms IF IT FALLS BELOW 11OHMS, OR VARIES SIGNIFICANTLY, THAT ALSO IS NOT GOOD.

Reconnected connector:
GRD/D1 5v 4.79v
GRD/D2 4.5v (closed)/ 0.5v (WOT) 0.514v / 3.52v I'M NOT SURE ABOUT THE 3.52V. MINE IS AROUND THE SAME . THE TPS FOR YOUR JEEP CANNOT BE ADJUSTED. DID YOU CHECK THE TPS AT THE CONNECTOR ON THE TPS?
GRD/D3 less than 0.1v .158v CHECK THE RESISTANCE OF THE GROUNDS IN THE ENGINE BAY. IT SHOULD BE <1 OHM, I THINK.
GRD/D14 Batt Voltage 11.56v
GRD/D16 Batt Voltage / 0v 11.55v / 0v

Click to expand...

Don't feel bad, I had to run through mine like 5 times to get it right. :looser:

In regards to your solenoids, there may be a few problems.
1. Bad grounds. Check the resistance of your engine grounds. Put one lead on the Bat neg and one lead on ground and test for ohms. I believe it should be <.1 ohms
2. Wacky wiring. There is a connector in the engine above the oil filter against the firewall. The connector is up high. Check the solenoid resistance there to rule out bad wiring between the engine bay and TCM. Also, make sure that the rest of the wiring is intact and in good condition.
3. The solenoids are just bad. You'll have to pull the pan to check them directly.

OK I really need to lay off the crack!!!! Went out and was playing again. Connector C3 came back, guess it was out getting a drink. The voltage is -0.91v, something tells me that isn't right.
The ground in the engine bay is 0.041 ohms.
And as far as the solenoids being bad would the switch method still work if they were bad? Because as it stands I can manually switch into 1, 2, 3, and OD.
Someone asked earlier if the tranny kicks out of OD if I goose the pedal. Don't think that it does but hard to tell with the tach not working properly (doesn't sound like it though). If I goose it with the selector in 3 the engine will not downshift either.

Haha. I did the same thing when I started too.

As far as your switch question, I don't know. I would assume that the solenoids would have to be good in order for them to work, since the switch essentially takes over the role of the TCM.

Try this, test C14-C16 at the TCM connector again to verify your readings. Then, if they are still wonky, test the connector in the engine bay to see if the resistance reads the same there as it does at the TCM connector. Do you want me to get you a picture of the connector?

With my problem, if I'm in '4', I can hit the pedal, and teh Jeep with downshift into '3'. The Jeep does not downshift from 3 to 2 though.

OK so haven't had time to really work on it as I am leaving this weekend... too much packing and such. But in my daily driving I have been able to feel the 3/OD shift both up and down. I know that was one of our questions.... If you could post a picture of the connector I would appreciate it as there is a bundle of four connectors in the area that you are mentioning (near the firewall, above the oil filter). Dunno if I am gonna be able to get it fixed before I leave but I will definitely seek out your advice upon return Alpha. I really appreciate it.

My 96 XJ did the same thing, exact same symptoms. I replaced the solenoids with new ones. That was 5 years ago and no more issues.

What I did, is I matched up the color wires that were in C14-16 to the wires going to the connector here. The connector is actually a darker gray, but the sun was doing something funny. This connector on my 95 is an 8 pin connector with only 7 wires. The end you'll need to test is the female end, IIRC.

Sorry to hear you are leaving us for the big sandbox. Don't be a stranger, and we'll see you when you get back. Thanks for your service.

xjtrailrider said:

My 96 XJ did the same thing, exact same symptoms. I replaced the solenoids with new ones. That was 5 years ago and no more issues.

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I'm about to pull my pan and test my solenoids. I have a feeling that's the problem.

Well I am in Iraq and wanted to thank everyone who was helping me work the issues out before i left. Will have to keep the solenoids in mind for when i get back home and can play with my favorite toy again.