Crankshaft Position Sensor Relearn

JeepSR · Sep 13, 2026

I have a 97 sport TJ that has never let me down. To the point I passed it down to my son. It recently started the stalling and shutting down at hotter operating temps. Like most, the CPS code was the only code. I did read that cheap sensors fail so opted for a NTK Sensor. Replaced and upon initial start runs fine. Then it reaches operating temps and does the same as before. I tried all of the manual relearn procedures like, pull ground off touch it to positive for 15 secs. Mash brakes for 30 secs to dump residual volts. Reconnect battery, turn key on, turn lights on then off. Turn key off and then start. Nothing has worked and I'm wondering if I have to have an OBD to do the relearn? It's a manual and has the 2 bolt sensor so I wouldn't think it would need the .034" spacer, but I've been wrong many times before.
Thanks..

hear · Sep 13, 2026

There's not really a learn mechanism on the 97 like there is on the later years (05-06 for sure, not sure about the others). I guess CPS = crank sensor in this case? The cam sensor performs much of the same function in much of the same way, but "2 bolt" describes the crank sensor. I've never had to jack with a spacer or anything, but that doesn't mean it's not important. But it's not where I would focus. If it fails at temperature, I tend to think electrical. These wires are now nearly 30 years old. Stuff gets brittle. I would particularly look at the section of the harness that goes behind the valve cover. There is a bolt there that tends to wear into the wiring. But all the sensors share a common 5V source & ground from the PCM, so a different bad sensor could cause problems elsewhere.

JeepSR · Sep 14, 2026

Yeah it's the Crankshaft Position Sensor, I figured it would show up in the title line where it asks for the subject of conversation. My fault.
I have looked at the wires and everything seems good. But that doesn't mean there isn't a problem in the wires. I'll do some voltage tests to see if we have a voltage drop at all. This one has me stumped.

TheBoogieman · Sep 14, 2026

When my 03' had similar issues, I replaced the cam and crankshaft sensors just to be sure. Not sure on a 97' though.

JKP · Sep 14, 2026

The cam sensor, aka synchronizer, or pickup coil, is in the distributor on a 97.

hear · Sep 14, 2026

JeepSR said:
Yeah it's the Crankshaft Position Sensor, I figured it would show up in the title line where it asks for the subject of conversation. My fault.
I have looked at the wires and everything seems good. But that doesn't mean there isn't a problem in the wires. I'll do some voltage tests to see if we have a voltage drop at all. This one has me stumped.

No, I probably just forgot about the subject after I clicked into the thread.

But what code(s) specifically?

JeepSR · Sep 14, 2026

hear said:
No, I probably just forgot about the subject after I clicked into the thread.

But what code(s) specifically?

The original code was an 0320 which was the crankshaft sensor. That's also the code the jeep threw up when I did the turn the key 3 times for self diagnosis. Once I replaced it no check engine and no OBD codes. I know when the crankshaft sensor isn't reading the tachometer won't move when trying to crank. It doesn't move at all. I spoke to NTK and the tech said it had to be taken to a shop for a relearn. He also went on to say it says that right on their website before you buy their products. If that's the case, I'm going to go ahead and change the cam sensor, idle air control, and TPS.
I love my 75 cj5 4.2; plug and play.

JKP · Sep 14, 2026

I'm not aware of any relearn on the 4.0s with a distributor, but mine is a 92 YJ and I've replaced the distributor (cam sensor) and crank sensor.

Normally you would only do a relearn after replacing the cam sensor. And that's just to set the cam/crank sensor difference in stored memory. Once started the PCM knows what the running cam/crank diff is.

Download the FSM under Resources.

@macleanflood is the '97 guy.

hear · Sep 14, 2026

I've got 2 97s and have replaced crank & cam sensors, and the complete dizzy; there is no relearn. Part of that is because the early cam sensor is materially different from the later years. The early cam is just an 50% duty cycle and that is synchronized to "1." The later years has more of a tone wheel setup with a trigger for each cylinder, so it has to communicate it's position relative to the crank and the hash it all out.

I mean, your tech should theoretically know more than the dude in the next cube here, but I'd be interested to know what he tells you the results of the relearn were.

Search

Search

Crankshaft Position Sensor Relearn

JeepSR

New Member

hear

Can't type

JeepSR

New Member

TheBoogieman

Disturbed

JKP

TJ Expert

hear

Can't type

JeepSR

New Member

JKP

TJ Expert

hear

Can't type

Similar threads