97 XJ Sport 4.0L Auto 4X4 Have been fighting a couple of transmission codes for a while. P0700 and P1898.

My searches have revealed that only the 97 models seem to suffer. Maybe since this was a “transition year”?

I have “poor man’s flush” twice. Replaced the screen. New NSS. Adjusted the TV Cable. Adjusted the shifter cable. Replaced the shift solenoids. Replaced the leaking lower radiator soft line with a new radiator. Jeep has 257K on it so maaaybe it’s just tired from the POs lack of true maint.

At a recent PullAPart run I took TCUs from a 98 and 99. Upon closer inspection I found that they connector on the TCU of the newer XJs are different. Just enough to prevent installation. Being a bit stupid, brave or ballsy I “modified” the connector with my Dremel and slapped the 99 TCU on my Jeep.

Now I get a P0700 and P0720 which points to the Output Speed Sensor. Yeah the really fun one to get to that costs $90. Have found the troubleshooting ( ohms check ) for the sensor. Planning on this next.

Honestly the Jeep seems to run just fine. But I hate having a CEL after pouring my blood sweat and tears into this thing for the last 18 months. Most that see it now don’t even think it’s the same Jeep.

Really just looking for some confirmation that I am taking the right steps.

Merry Christmas!

 

You need a TCM for a '97. In '98 a second trans speed sensor was added (Input Speed Sensor) so the 98/99 TCM will be looking for that sensor, which isn't there in your '97. You should reinstall your '97 TCM and go back to resolve the P1898 issue.

You're right, P1898 is a '97 only code - No signal from the solenoids.

Here's a pinout of the '97 TCM connector.

Measure the resistance (in turn) from pin cavities 11, 12, and 13 to pin cavity 24. The resistance should be between 11 and 15 Ohms.

 

CCKen thanks for the validation and code description. Could I ask where that code was listed? Have been frustrated in the past that I couldn't come up with anything on it. Have found a local wrench ( ex dealer/factory guy ) with a DRB that I was going to set an appointment with next. Thought maybe there was a firmware update that could be done. Maybe? Also since it's a signal code error ( I'm reading WIRING ) I will make sure that I check/clean the under-hood connectors.

 

Can't remember where I got that data but I penciled it in at the end of the DTC listing in my '99 FSM. I think I've only heard of it referred to once.

Do the resistance checks I oulined to see if it is a wiring problem from the TCM connector to the solenoids.

If you get higher than spec readings, measure the resistance from pin cavity 24 to chassis ground. The ground for the TCM is at the coil attach bracket studs. If the ring terminals at this ground point are corroded it will screw up your readings, and the TCM as well. Look for lower than 5 Ohms resistance. Zero Ohms is desired.

Don't forget the correct year TCM is required.

 

Did you ever figure out your issue? Been fighting the same codes myself..