M & S lights flashing,limp mode, need help!?!?
 

Gents,
I've had quite the issue this last month with a set of M & S lights flashing on my 03 Disco. I still haven't fixed the problem, so after reading every thread on here I could find, here is my issue.

First, the symptoms...

TC and Downhill Descent lights illuminate, followed by...
M & S flashing lights, followed by...
Limp Mode (drives like crap)
This happens only after getting the engine to the normal operating temperature, and usually only after having done some highway (70mph, 10-25 miles) driving and then slowing back down and doing city driving. It rarely happens from city-only driving.

What I thought was the root cause...

Originally, I had the 3 Amigos pop up almost immediately when driving followed immediately by the M & S lights. I bypassed the sensor following the sticky I found on the website, and it fixed my SVS issue, which delayed the M & S lights. Unfortunately, after a bit of driving, I got 2 Amigos (TC and Downhill Descent), and then the M & S lights accompanied with limp mode. I also had both the battery and alternator checked out and they were well within range. The battery is less than a year old, and the alternator was cranking out 13.9V.

Various Codes...

I had codes for a faulty MAF and TPS. I replaced both and this did not alleviate any issues. In fact, I still receive the same codes for both from time to time.

I also had codes from my ABS Amigo that included a faulty SVS (hence the "fix"), and a PWM Signal Failure.

When the two remaining Amigos flash, my code is the "PWM Signal Failure".

What I've checked...

After replacing the MAF and TPS, I checked the continuity of all the associated wires and found them to have no resistance, so that should rule out bad wiring.

I checked all of the harness terminals to ensure a tight connection, and they weren't loose.

My throttle cable was very loose and I adjusted it to the spec I found in the RAVE manual. This did not alleviate or cure my problem.


Mechanic...

After checking and testing all of these things, I took my Disco into an independent LR shop. Using Autologic, they have found the following issues...

From SLABS: "PWM Signal Failure from Engine ECU"

From the Trans: "CAN message WFPDK (DKI) invalid (FFh)."
"CAN message PHOEHE invalid (FFh).

The shop informed me that they tested the TPS (I re-installed the original) and that it was working properly, but perhaps when the engine was hot it was causing some resistance which was sending the code putting me into limp mode. Their solution was to replace the TPS and try that. Having just installed a new TPS (which I removed prior to going to the shop), I didn't think it was a great idea as it did not solve the problem either.

Where would be the next place to start looking? I'm frustrated to the point where I want to start throwing parts at it, but my pocket book isn't okay with that idea yet. Any ideas or advice is greatly appreciated. Thanks!

My 03 had this M and S light flash, and limp home in 3rd or 4th or something. It would only do this after a getting warm, driving most of the way home. Sometimes it would die and not want to restart. Usually turning the key off and sitting for a bit and it would start again. It had a code for the crank sensor. I got one at autozone, which even though in a different bag it was a bosch sensor just like the original.

I'm not suggesting you throw parts at it, but you might try another scanner and see if you get another code. I borrowed a friend's obd-ii scanner and it seems just about every car I connect it to it finds some sort of evap code that may or may not be there. ;-)

Same symptoms for me, crank position sensor

I had the same M & S problem...and actually they just came up again yesterday (frick!). Here's what some of the helpful forum guys suggested to me.

I'd recommend first getting your battery and alternator tested at your local auto parts store first. They do this for free. They should test both "under load" as well.
Make sure you actually write down the numbers - because my battery and alt both "passed" according to their general equipment, but once I reported the numbers here it was clear my alternator was "below acceptable". I believe it needs to be 13.6 or above (don't quote me on that). It fixed my problem (for the time being, of course)

I'm passing on helpful info that was given to me...
I *believe* these lights flash as a result of the trans ECU not getting enough power and therefore putting the rig in "limp mode" (3rd gear only). This explains why the car is so sluggish off the line and never shifts. You aren't supposed to drive it and the manual calls for shutting it off and restarting.

Where did you come up with a crank sensor? That is a really bad "GUESS".

I would take it to a dealership and have a Certified Land Rover Technician diag this, sounds like a problem car.

Unfortunately, a dealership is not a luxury I have. Having the car towed 2.5 hours is a bit too much.

Not sure if this helps but here goes.

Check to see if the vehicle speed signal (VSS) has failed indicated by code P0500 or P0501. Signal from the VSS is used by the SLAB ECU to generate PWM communicated over the CAN bus. VSS failure could cause PWM signal failure and make the TC and HDC lights illuminate. A PWM signal fault could cause M and S light illumination and limp mode. One of the following codes should also be present.

P1841 (16) * Fault description CAN bus fault Effect Maintains current gear in low range, limp home mode in high range. Shift pressure to maximum, harsh gear shifts/engagement.

P1842 (15) * Fault description CAN level monitoring Effect Maintains current gear in low range, limp home mode in range. Shift pressure to maximum, harsh gear shifts/engagement.

P1843 (17) * Fault description CAN time-out monitoring Effect Maintains current gear in low range, limp home mode in high range. Shift pressure to maximum, harsh gear shifts/engagement.

P1884 (18) * Fault description CAN message: Throttle position invalid Substitute throttle angle of 50% adopted. Effect No kickdown. Operates in economy modes only.

P1884 (35) * Fault description CAN message: Engine speed invalid Effect Maintains current gear in low range, limp home mode in high range. Shift pressure to maximum, harsh gear shifts/engagement.

P1884 (35) * Fault description CAN message: Engine speed invalid Maintains current gear in low range, limp home mode in high range. Shift pressure to maximum, harsh gear shifts/engagement.

Refer to RAVE Manual pages 18-2-55 and 44-18 through 44-20.

P1884, how is this corrected. My 03 is giving me this code. Thanks.

Clean your xyz switch and put new grease in.