Thank you for all your contributions on the topic on M & S flashing, I realize that the topic was discussed many times, below is my problem with the M & S lights flashing on my Disco II 2003, 4.0L V8. Mileage:78,000 miles

Bought the car and drove it for 11 straight months without any issues, one day in Nov 14, I had a dead battery which I changed into new. Later, in Feb, I got the M & S flashing on the dashboard while driving, stopped the engine, and restarted and all clear for another month or so. Later in April, I got the error again, it was more stubborn this time, it would go only if I clear it with my OBD device, until a week later when it was permanently on, and while diagnosing the error, I was given P0335 which indicated that something could be wrong with Crankshaft Positioning Sensor, which I replaced with a used one that was readily available with my mechanic, and the error has gone for a week, and then got back, decided to get a new one, waited for 2 weeks (online order to East Africa) and fitted the new one, and was good for only another week.
Now it is June and I’m still getting the error every day, but there is a pattern now. Early in the mornings (cool weather) when I’m off to drop the kids to school (Tropical weather all year round). I reverse the car back out of the garage or drive straight out of the garage (depending on how I entered the garage earlier). I drive a bit on a slight slope, a minute of driving later, 2 scenarios can occur:
Scenario 1: The engine roughs up a bit and the M & S lights come up along with the ‘Check Engine’ light. The car gearbox switches to limp mode and drives on third gear, when this happens I park and stop the engine, clear the error with OBD, and drive normally for the rest of the day.

Scenario 2: If I manage to detect the roughing up of the engine before the M& S lights start flashing, I go in ‘N’ quickly, then back to ‘D’ and no error, and I keep driving the car normally all day long.

Note: I get the error more or less at the same spot every day.

Now, I’m puzzled to whether this could be related to:

1-A battery issue, when I change the dead battery, I had to go for a Korean brand that was widely available in the market, Hyundai Enercell 12V, 70Ah, 750CCA. Could be that the battery was in perfect condition when I bought it 7 months ago? And now it is acting up!? Would a 90Ah battery do a better job? Would it affect anything negatively?
2-Or is it the Alternator, affected by a battery that is acting up? Or just the alternator?
3-Could be the XYZ gear selector switch? I have intentionally listed this till the end, because I believe that it is ok, and I would like to think of it as the last culprit, because it is expensive and is a delicate process to replace.

As indicated above, I have also tried to reverse the car in the garage and drive out on ‘D’ not on ‘R’ as I used to do, same result. I have also have done the test of switching the wipers on, and engaging the gear on ‘R’, the rear wiper works fine perfectly, every time I try it.
Any insight or help from experience would be appreciated,

 

What is your alternator output and how many amps is your battery rates at? Not Amp hours, amps?

 

The alternator is the original one, I guess its labeled manufacturer output is 130A, beyond that I don’t know how measure anything related to alternators. However, I did some tests last night and this morning with my multimeter, and this is what I found.

10PM last night … voltage 12.75v measured 2.5 hrs after last run

Battery voltage following morning 12.65v (before starting engine), I also load-tested the battery by switching on the headlights, voltage came down to12.25v

A minute after starting the engine, voltage measured a max of 14.15v (no load)

Kept engine running for some 5 minutes then drove for 2 minutes, cleared the M&S lights flashing with OBD device, continued my trip for another few minutes, and came back home, kept engine running, measured voltage was 13.75v

Kept engine running at garage, and switched on all possible combinations of electricals (AC, High beam headlights, fog lights, CD player) voltage 13.5v

My battery is a generic 70Ah 750CCA battery; I’m not confidant enough to use my multimeter to get the battery amperage.

I hope the above helps in any way,

 

Well your alternator is charging which is good. An autostore will do a real load test on your battrey for free, with the hope of selling a new one. That leave a bad ground or xyz switch. I dont know if it will work, but run a temp. ground from the battery to the engine see if that stop the m&s.

 

I Just had same issue. My positive terminal connection wasn't good and my positive cables were corroded under the red insulation. Cleaned everything and replaced terminal connector with new one. M and S went away immediately and have not returned. The system needs a steady flow of power, if it fluctuates any, the warning lights will come on and codes start being tripped. It could be the ground connection too, or it could be both. I bet it is one or the other though.

 

FFS don't attempt to measure the amperage across the battery using a multimeter 'cos it'll go into meltdown or blow the fuse. You require a special high amperage battery tester for a flash test which should only be for 10 seconds or less. The max amperage output in a healthy 12V car battery is huge, enough to melt your metal watch strap if you touch it across the terminals accidentally (I know a guy who received severe wrist burns doing exactly that) .

 

My guess is it's your xyz selector switch if your battery and alternator is giving the correct voltage outputs. The xyz switch is repairable and requires internal cleaning and re-greasing ensuring the contact tracks are all working and making contact OK. Use Vaseline waterproof grease to re-grease the switch internals and ensure you extend and re-direct your A/C drain away from above the switch because it drips water onto the connector plug, crap LR design.

 

My voltage was reading correctly too......while the vehicle was not moving and shaking around. Not saying it isn't XYZ, just before you can start trying to diagnose electrical issues, you must first be 100% sure your power/ground is absolutely working properly.

 

If you research other forums, you will see most of the time it was battery/connection related. Which also happens to be my experience. However, it could the XYZ, but just do the easy and less expensive stuff first, bc according to the stats, that is the problem most of the time anyway.

 

Thank you all for your replies, I have replaced my under warranty battery yesterday, it was tested at dealer's shop, the recommendation by the machine was to 'Replace Battery', especially when the CCA was tested, it gave 625CCA instead of 750ish CCA (I understand CCA is not crucial with petrol engines). As for alternator charging, it seemed normal with no issues.

I drove the car this morning, and at almost exactly the same spot I got the M&S lights flashing again, cleared them, drove the car normally.

So I guess I'm off to ordering one XYZ switch online. I can't do the job of cleaning it. I found a used one for 285$, anyone has any thoughts on used ones with warranty?