help...M and S lights flashing and shifting weird

[jseufert]

My disco2 is an '01. I haven't had any issues, until now. I've seen this in the forum sort of. I was driving to work and 10 minutes in the truck did a jerky shift and then my M and S mode lights came on and started flashing along with the Drive indicator. I pulled over and turned the car off, waited a minute and started it back up and everything was fine for the rest of my 50 minute drive. Then the next morning, my truck took more time than normal to fire up. Usually I can turn the key and it starts right up. But this time, I had to turn the key 5 times and hold for about 5 seconds before it fired up. Then again, 10 minutes into my drive, the weird shift happened and the m&s lights start flashing.

So I read here that this could be the battery. I checked my battery and it was at 12.6 volts. I charged it up and it was at 13.6 volts, which seems to be the magic number. well...same issue. Where do I go next?

I really don't beleive it's the xyz switch. Could it be the alternator? This was changed about a year ago. The battery is about 2 years old and clean, no corrosion but low. I just can't believe a 12.6 volt battery causes this big of and issue.

Thanks, JS

[GuyD]

It is definitely an electrical problem.

Check all of your wiring for a loose connection. My problem was a connection near the fuse box under the hood.

Once I tightened it, the problem went away for good.

[jseufert]

Thanks Guy, I checked around for loose connection and can't seem to find any. But now I have a new problem.

The other day on my way home, on the highway, my truck just turned off. The tach spiked real quick and then down to zero. I managed to get it over to the side of the road and it stared back up and I made it home. The service engine light did come on.

This morning, I had a hard time getting it started, but I did get it started. Then I was driving and it just died on me again. The service engine light did come on, but also seems to have cleared itself and wasn't on when I got it stared again. So i parked it and took the battery and alternator up to autozone and had them tested. Both checked out fine. Is this a crankshaft sensor issue?

[Prodigy999]

Originally Posted by jseufert

Is this a crankshaft sensor issue?

yes.

[Disco Mike]

12.6 will throw the tranny's ECU nuts. Clean and tighten your cables, go by a local auto parts store and have them do a free battery/alternator test, you need 13,6 to 14.4 or you will have problems.

[jseufert]

So what battery do I need?