Amelie

Hello everyone,

so my hubs and me a re little bit at our wits end.

My '96 Grand Cherokee stranded me the other day at a gas station. My FIL was able to jump start it. After that we figured out that it muss be the NSS so we had it replaced at a garage.

On my way to work today it started shifting oddly. It shifted fine from 1st to 2nd but very late or not at all from 2nd to 3rd and to 4th. After stopping and turning it off and back on it worked fine for a while until it started again. By that time I had made it to work.
It started right up when I turned it on after work but started with the shifting issue again. So I stopped on a parking lot and now it won't start anymore.
I was lucky enough that it was an O'reillys parking lot. We got the OBD and it showed the code P0645. After some googling and research on this forum I found out it is "P0645 A/C Clutch Relay Circuit An open or shorted condition detected in the A/C clutch relay control circuit."

Now I am confused. Could this keep my car from starting? It doesn't crank. My hubs says there is no power to the starter. He tried to jump the solenoid and it didn't work.
It doesn't start in neutral either. No wiggling around of the shifter did anything either.

The battery is fine. It has 14V and all the lights on the dashboard come one and the radio and windows work.

I don't know if it's necessary to mention it but it's an automatic, that's why the clutch relay confuses me.

Maybe some of you have an idea what it could be?

Bustedback

That code will not keep the engine from starting.

Amelie

I wonder if it could be the NSS again then.

Is there a way to check it? Or bypass it to see if that would solve the issue?

dave1123

I would check for a loose or corroded battery terminal clamp. Those molded lead clamps stretch and feel tight, but don't clamp the post tight enough. Low voltage in the system can cause all kinds of weird things to happen. Look also at where the cables come out of the terminals. They can corrode inside. On the red cable, there are 2 wires coming out. One goes directly to the starter solenoid and the other goes to the fuse/relay box under the hood. You may have a bad connection on just the one that goes to the starter.

Amelie

In case anyone wonders.
We figured out the problem. The battery was not giving off enough voltage even though it tested fine at first. We charged it fully up and the car started but still shifted weirdly.
We ended up realizing the car was low on literally any fluid possible and imaginable (I guess it's a newbie error to not check that first). The. We took it to a garage because it still seems to shift oddly. We were told the replace the spees sensor switch on the TC but after doing some reading on it I am not convinced that it actually has anything to do with the way the car shifts.
We also changed the valve cover gasket. The inside was really clean. No vracks, no water. Now if we could solve those shifting issues it would be a great car ready to get fixed up for 4 wheelin.