Bought 2000 D2 with it limp mode. It has a lot instrument cluster icons lit: S M flashing and a few others. It’s stuck in 3rd gear. I read a lot on this forum and the prior owner swapped the XYZ switch but didn’t fix. Just for troubleshooting I ordered another XYZ from eBay and installed that properly I think. But still stuck in 3rd gear.

Any ideas thoughts at all would be helpful. I got my engine all fixed up maintenance wise and it’s running great other than stuck in limp mode. So this now my current project. Please let me know you think I should check anything or I do have okay scanner I can pull data or check something in there.

anyways thanks!

 

Very, very frequently, the flashing M&S indicators and limp mode are triggered by an electrical problem inhibiting good voltage to the transmission ECU.

This forum has many, many threads about this. Start by cleaning and double or triple checking the battery connections. The trans ECU is infamously fickle about voltage.

If that doesn’t work, the RAVE Workshop Manual lists 14 different faults that can trigger the M&S lights plus limp mode. Unless you get the codes read with a diagnostic tool capable of reading the trans codes you are just guessing. It saddens me to read about so many people wasting money on XYZ switches because it’s the part easiest to replace.

Do you have the RAVE Workshop Manual? If not, you can download a free copy from the link in my signature below.

Where are you located? There may be forum member nearby with a diagnostic tool who'd be happy to help.

 

As Min says, it is very likely a voltage to the Transmission ECU issue. This could be as simple as weak (corroded or loose) wiring connections, or a weak Alternator. The trans ECU is very picky about the voltage it gets.
Also, make sure that the transmission fluid is at the correct level. You need to check the level exactly per the manual.

 

A simple faulty alternator (common) will stick the transmission in limo mode. Check battery voltage at terminals while running before digging into anything else. I always like to start with simple and easy with diagnostics

 

Okay this is very helpful. I do have a rave manual. The truck has MAJOR wiring problems that i have since corrected everything except this s m light limp mode deal. I found the wiring harness was torn and cut at the point in which it runs to the two driver side cat O2 sensors and then goes up and over the trans area for the rear pass O2 sensor. I have since spliced in new wiring harness from this point to repair using a donor harness from ebay and the oxygen sensors are back online and communicating data via the scanner real time diagnostics.

So i would NOT be at all surprised if there is something off with the trans ECU wiring. That does give me a good target to begin my new battle effort. I'm in Minnesota - i don't nanocom or whatever, but i decent diagnostic tool just not that one which i know is much better. I guess I will go right to the Trans ECU and check the wiring starting from there, clean it up make sure it appears functional and try track back and see i can find anything. As far I know ... I fixed the entire wiring system - i don't have anything indicating any wiring problems anymore other than this limp mode situation.

So other than going right at the trans ECU connection point and double checking... what else would you recommend? If it is not too much trouble... I have been having trouble finding things in the RAVE manual. Sorta new to it and mainly just working off knowledge of what i know about autos to fix this thing. If you are able to CC those 14 faults or let me know what pages there are on that would super helpful!

Really appreciate the help - keep ya'll updated. This is pretty much the final thing i need to fix and then i can start going to town on fun upgrades - lift kit, tires etc.

 

faulty alternator? Truck would not stay running tho yeah if that was the case or are you saying a faulty enough to run it just kicking it to limp mode from not enough power maybe? thanks!

 

aulty alternator? Truck would not stay running tho yeah if that was the case or are you saying a faulty enough to run it just kicking it to limp mode from not enough power maybe? thanks!

 

Weak alternator ... hmm

Is that something if i removed and took to a auto parts store they can check or? Remains running fine so appears to be producing power maybe not enough tho you say? I don't really know how to go about testing it manually myself to see if it working properly. If take it to auto parts shop can they test this or should i try get a new one swap it see if that works?

 

BTW this is auto trans... not sure that makes a difference with regard to what you were saying?

 

All factory disco 2 models are automatic.

And yes, a weak (faulty) alternator will kick the transmission into limp mode. My significant other drove home 20 miles due to this not long after we took ownership. Was and easy diagnosis and fix but was a little over 200 bucks.

​​​​wasnt weak enough to kill the battery but wasn't enough to keep the tcu happy.