ltljon

99 automatic-(RHD if it matters) Wants to take off in 2nd gear only regardless of where shift selector is. All other gears shift smooth.
Started doing it a little more each day when it got hotter but would work correctly after it completely cooled down. Now cool down doesn't help.
Had codes PO758 & PO720 come up at Autozone. Checked connections but haven't replaced sensors.
Garage said maybe solenoids inside pan? He admitted trans wasn't his strong suit.

CCKen

P0720 is OUTPUT SHAFT SPEED SENSOR ERROR

P0758 doesn't exist.

When I get my photobucket up and running I have pics of the Output Speed Sensor (OSS) and the pinut of the TCM connector where you can check the resistance of the OSS to see if it's dead. It should be 625 Ohms.

NOT an easy task to change this bugger because it's behind the TC shift linkage bracket.

CCKen

Here's an image of the location of the Output Speed Sensor (OSS) on the AW4:



Here's an image of the OSS:



Here's a pinout of the Transmission Control Module connector where you would take your reading of the OSS.



Disconnect the battery negative post connector.

Using a quality digital Ohmmeter you will read between pin cavities 3 and 4 on the TCM connector. You should see around 625 Ohms. If you read an Open, or very high or low resistance the OSS may be defective or the wiring between the TCM connector and the OSS has problems.

I have no idea where the TCM is on a RHD XJ, but on the LHD version it's located under the dash just to the right of the steering column. I guess you'll have to find yours. It's a small silver-like box.

Take your readings and get back.
.

ltljon

My apologies, not sure how I misread that! It's PO753.

The wiring on the Input Speed Sensor had been messed with before. It was wound up with electrical tape as the housing for the wire side was gone. I pulled it off, cleaned, re-attached but no change there. The Output Sensor didn't seem to have been messed with. Will try Ohming them both out tomorrow.
Since they're throwing the code is it a pretty good possibility they're the culprit for no 1st gear?
The guy at the garage couldn't find the TCM but kept looking under the hood.
It's probably where you suggest. It's amazing how many things are backwards of a LHD.
Thanks for your feedback.

ltljon

Found silver box about 3" square with bolt in middle?
I'm thinking it'll be easier to take the seat out & lay on my back to get under there. I might coulda wiggled my way in there 30 years ago!

CCKen

Bolt in the middle(?). I don't think so.

Google "Google Images", then enter "Jeep Cherokee Transmission Control Module". You should get some pics of the TCM.

CCKen

When you find the TCM you can read the resistance of the solenoids from the TCM connector. Ref P0753.

Read from 11 to 24 (Ground), 12 to 24, and 13 to 24. Each solenoid should read between 12-15 Ohms.

ltljon

Well, I looked again & there is a PO758 as well as 753 & 720 (I had 3 printouts instead of 2)-shift solenoid circuit fail.

Actually had 6 total but the other 3 were 2 for timing belt & 1 for a fan relay.
PO340, P1391, & P1491.
Could 758 just be an Autozone number?

CCKen

Does you Jeep even run?

I have a feeling the scanner/code reader Idiotzone used wasn't programmed for a Jeep 4.0. 758 must be for some other vehicle.

ltljon

Unbelievably it runs great. You wouldn't think so with all the codes though.

Haven't had chance to look for TCM yet but pics show it may be in center of dash or below steering wheel.

CCKen

Clear the codes by disconnecting the battery negative post connector for about 5 minutes then reconnect. Next time you have the codes read go somewhere else, if you can.

I just looked in a 2000 XJ FSM and it shows the connector for the RHD TCM to the left of the steering column, to the right of the trans tunnel, mounted high. A mirror image of the LHD XJ's.

ltljon

I got 14 on all 3. I tried the jump between 3 & 4 but couldn't make a good enough connection to get a reading. The meter did jump numbers once but that's it. I guess my probes are too big for the holes. Was tough getting reading on the others but it was a solid 14.

CCKen

Don't shove the meter probe into the pin cavities, you will enlarge them so the pin will not make good contact when you reinstall the connector. All you have to do is touch the cavity with the probe.

Try reading from 1 to 2 (input speed sensor).

14 Ohms on the solenoids is good.

Your issue is with the output speed sensor so see if you can read it.

ltljon

I've tried 2 different meters & cannot get a reading. It will occasionally flash some numbers when moving the probe around but only for a split second. I can see & feel I'm touching the metal of the connector.
The pin connector you posted pic of is a little different than mine. Mine has the same number on each row (13) but on the far right mine has 3 larger pin holes where your pic shows 2. Could this make any difference on which ones I should be touching?

ltljon

Ahh, my issue may have been with the meter setting. I had it on 200 & needed it on 2000.
Anyways, got 626 between 1 & 2, couldn't get anything on 3 & 4.
Was still hard to make good connection on either but didn't even get the flash of a number this time on 3 & 4.