Thread: M & S lights....yet again :(

Originally Posted by 2 rocks

Right
So I've had this intermittent problem with M&S lights coming on and the trans going into limp home for while...mainly parking etc (shifting between P, D & R). This is usually resolved by switching off & restarting.

Yesterday came on and wouldn't clear. Now I know the manual says "electrical fault with the 'box".

Anyway - same this morning so got underneath:
1. there are two "spare" connectors off the transfer and two spare connectors on the g-box loom (probably irrelevant).
2. jigled all connections, had go at the sensor near the aircon outlet

No change.

Then shifted to Neutral and started - lights out! Quick drive to shops and back no problem.

Now I'm wondering what this suggests to your learned minds? Problem with selector contacts? Problem with g-box control module? Something else?

The car is pretty much everything I want now, but I feel I can't trust the transmission yet for a trip...

Mike

I had this when my battery was on the way out, on and off for a while. Thing was I did not know the battery was going at the time. Battery died, new battery in, had logged a fault code, cleared code and and six months later no problems. Try a new battery if it's a few years old. I think the dying battery clause low volatage and the car goes into limp mode to protect the engine.

Originally Posted by 2 rocks

Right
So I've had this intermittent problem with M&S lights coming on and the trans going into limp home for while...
...
Now I'm wondering what this suggests to your learned minds? Problem with selector contacts? Problem with g-box control module? Something else?

Mike

Hi Mike, I'm not Tony, I'm just visiting him, but I do have a little experience with modern electronic automatic gearboxes.

First comment, in many cars the transmission and the engine have seperate control modules. The engine module controls the transmission fault codes.

I've just been through a problem with a Rodeo where the fuse supplying the gearbox blew, though I didn't recognise that this was the problem for a rather anxious hour or so.

The gearbox then has no 12V power at all, so the engine module then detects that the gearbox isn't talking to it and flags a fault. In the Rodeo a "check trans" light flashes. The gearbox can then be manually selected to limp home. Note that the fault is not strictly with the gearbox, it's with the 12V supply to the gearbox.


Same car, same gearbox, different fault 18 months ago - when I first test drove it from a car yard it had a very flat battery. This resulted in a different symptom. The engine management system coped and once jump started it would idle despite having maybe 6V at the battery. This was enough voltage to drive the gearbox "brain", so the engine module didn't flag any fault. But there was insuffiient voltage to drive the gearbox innards to actually open and close the right valves to select the required clutches and bands to engage a gear. So at idle there was no drive in any gear. As soon as the engine revs rose above idle and the alternator pushed the voltage into more normal 12 Volt territory, the gearbox would grab (eeks!) and the car would drive normally. A fresh battery fixed this completely.

The message in both these cases is that a perfectly healthy electronic gearbox still needs it supply of good clean 12 Volts. Your problem certainly sounds like an intermittent electrical fault and it's unlikely to be inside the box.

I'd be looking for faults which may be compromising the 12V supply to the box.

My recent fault, the blown fuse, was caused by a faulty trailer. My gearbox shares it's fuse with the indicators and reversing light. If the short in the trailer had not been enough to blow the fuse, I would have had an intermittent low supply voltage to the gearbox whih would have looked a lot like your fault.

Look for things that are on the same circuit as the transmission. See if any of them also fail when the gearbox is on strike. See if you can find the 12V supply into the gearbox *at the gearbox* and measure the voltage present there when the fault is happening.

If the supply into the gearbox is good, your problem is likely to be one of the other sensors or other connections to the box. Control modules are pretty robust and well protected, whereas wiring and connectors are often damaged. I'm not familiar with your particular gearbox, but if you can find other wiring into the box, identify what it is and find out what voltages should be present when, then check they are right.

My apologies for any weird spelling with no "c", the C on this keyboard is diky. See what I mean.

Good luk. Again.

Graham who is not Tony.

Thanks guys
Looking at the battery, it does look like it's done a few miles...

Graham
Very interesting! It's due in for a service next week, so I might ask them to check all the connections and the power supply too.

Someone previously had mentioned earthing points accessed via the rear ashtray in the console. My problem there is - previous owner fitted a DVD system and there is no rear ashtray and a bunch of wiring i can see near the heater vents. I just hope they didn't use those earths for the DVD system...

Cheers
Mike (I promise to get the Pajero off my avatar today!)

AK !!!!!!!!!!!!!!!

I'm not counting my chickens yet but looks like you may be the winner!

Just went down to the shops and the old dear didn't want to start...cranked over sluggishly until the auxilliary kicked in when the volts dropped away.

So it may well be the battery - I bloody hope so!
Except...the RAC won't deliver out to me and it's now 5pm on Sunday. Thank you Mr Murphy!

Cheers
Mike

Originally Posted by 2 rocks

AK !!!!!!!!!!!!!!!

I'm not counting my chickens yet but looks like you may be the winner!

Just went down to the shops and the old dear didn't want to start...cranked over sluggishly until the auxilliary kicked in when the volts dropped away.

So it may well be the battery - I bloody hope so!
Except...the RAC won't deliver out to me and it's now 5pm on Sunday. Thank you Mr Murphy!

Cheers
Mike

Yep even with mine after a battery test it showed enough volts to start the car then a few months later the battery just died with no warning except for the M&S lights and dropping into limp mode.

Don't care if I am the winner or not but hope it is as simple as this and the only cost to you will be a new battery. After the new battery it would be worth your while getting the fault codes cleared. Cheers.

The M&S lights will also come on sometimes when u turn they key on and of a few times (last time on mine when I replaced the fuel pump and bled the lines). Probly to do with voltage as well, tends to clear itself no worries, drive a short distance, stop, and restart.

Dave

Well, turned out was a few things really, with the dash lit up like christmas...

Battery had a collapsed cell - new battery - no more M&S lights, but TC & ABS & CDL still on. Was told the CDL light can sometimes be caused by a faulty brake light, so...got home, removed and refitted all stop/tail & indicator globes to be sure.

Then crawled underneath again...hmm funny little loop of wiring hanging down off the X-fer case...yes the one that's been rubbing on the cardan joint, the one that's worn through to the copper core. Looped it up out of the way...no more CDL, TC or ABS warnings. The boys can fix that properly at the next service!

No problem yesterday or today with the M&S lights, even when trying to induce it...until tonight. Happened again but cleared after ignition off.

I therefore assume that this must be a problem with the selector and or sensors that relate to this. I really want to resolve this once and for all - new transmission maybe????? Gaaaaawd!

Mike

My Dad had similair trouble with his DII. It turned out to be the "reverse gear selector" or words to that effect. I can't exactly remember but it is along those lines.

The problem would manifest itself if the first time the car was placed in gear after start up was reverse gear. Problem was fixed by turning the ignition off then on again. It is an auto by the way.