Transmission codes...making them go away?

Here is my situation.

'98 Cherokee Sport. 4dr/4wd 4l, automatic



I had a problem with my interior lights staying on. I pulled the interior light fuse in the PDC and ran the vehicle for awhile. Basically you have no gauges, interior lights or door locks. Eventually I found my problem to be a bad dome light in the back. Replaced the fuse.

Now I have a Check Engine Light (CEL). I need to get the vehicle inspected here in NC and to do so you need the CEL gone.

I take the Vehicle to Advance for a code check, I have a PO700 and a PO715. 700 is auto trans malfunction/715 is a speed sensor malfunction.
Advance clears the codes and I drive home. Vehicle shifts normal, down shift normal. NSS allows it to start in Park and Nuetral as expected Everything is working normally. 5 minutes of driving after clearing codes I get CEL back.

Reading here and other forums it appears there are engine codes, and other codes. Other codes do no clear like engine codes. The fuse I had out for my initial interior light issue also powers the Transmission Control Unit (TCU).
What I think happened is while I had that fuse out the transmission was not getting proper voltage or signals and threw the codes. Now that it is all back it is not clearing those codes and therefore CEL is staying on.

Does this make sense to anyone, and does anyone know how to clear these
codes? One internet site told me to disconnect TCU, did that without luck. Disconnected battery for a while, no luck. Connected battery terminals together, no luck. These methods usually clear codes, but not in this situation.

Any help would be appreciated.

I would start by checking the input voltage and DC return lines at the TCU connector.

You have to repair the problem. You MIL came back on because there is still a problem. You know after you repair the problem, you have to drive it long enough to get at least all but two readness codes before you can get an emissions inspection in NC. If you clear the DTCs and go right to the inspection station, you will be rejected.

My FSM shows no P0715. It jumps from p0713 to p0720.

Sure it's not P0700 (MFR Transmission Controller Failure) and P0705 (Range control switch)? If it is the P0705, look to the NSS. Prolly dirty. Lots of threads and internet articles on how to clean and adjust.

Take it back and read the codes again.

I took it twice and got the PO700 and PO715 both times.

The PO715 would be a problem with the front input speed sensor. Its on the drivers side of the tranny, mid-way up, forward near the bellhousing. I would suggest inspecting the wiring to it. With the engine running, tranny in park, you should see some a/c voltage coming off the sensor (its a pickup similar to to the crank sensor).

That sensor isn't critical. It was added in 97/98 to aid in self diagnosis (eg figuring out what gear the tranny is really in). Aside from throwing the error code, its not likely to affect how its shifting.