I've started getting the M&S Light more and more often of late, so as the truck was going in for the manifold gasket, I figured I'd ask them to double check my diagnosis, and sort out the XY switch too.

Typically the truck behaved perfectly, with no gearbox lights at all, and they were honest enough to say that they would advise not changing the switch unless they could have the fault live in front of them

However, they did price up the replacement, and it's currently going for about £300! I thought they were nearer £120, but a google has found that they all seem to be about this much now. Anyone know WHY? is there a world shortage or summat?

Anyway, I have now got myself a Hawkeye so decided to hook it up and look at the live data to see if I can work out what might be going on. Running home tonight, it was giving me messages like 1100 (Invalid) D. when a gear is selected (the number and PRD123 appears alongside the Invalid. With the selector between positions, the message is INTERMEDIATE.

Is this correct. Which input is invalid?

Also It's only showing 13.89 Battery volts. DOes this mean that the ECU is seeing a low voltage? I read that this can be a problem. I've just fitted a new battery, but think perhaps the alternator may need to be checked out.

Many thanks

MW

If you are seeing the invalid message in live data when shifting through the gate with the car stationary and engine off then you can be fairly sure its the WXYZ switch at fault.If it is in good nick it should flip through the positons as fast as you move the lever.It should only show PRND321 no matter what you do.The invalid signal is shown when the EAT ecu receives implausible data.13.89v is fine whilst running,read from the EAT ecu,the faults that people bang on about from low batteries are when the voltage drops when the ecu is booting up and the engine is cranking at the same time.The EAT loom rubbing through is more likely to give the invalid signal when the car is moving,ie the engine and box moving on its mountings under acceleration / decelleration.The damage to the loom should be fairly obvious if you lift it up at the back of the transfer box,either way its a good idea to check it.If you fit a new WXYZ switch make sure you adjust it properly on its slots to give the correct reading to the ecu.

Thanks.

So do I understand correctly that an (Invalid) whilst driving along, with no other faults or warning lights clearly indicates the switch is at fault?
The PRND123 is matching the selection, and moves really quickly.

Strange the specialist didn't spot it, but they have offered to have it back, with no further costs for diagnosis if it re-occurs.

Still leaves me facing that bill for a poxy switch! Are they making them from unobtanium now?

MW

No, read my post again,with the car and engine at rest getting an invalid message usually is the WXYZ switch.With the car moving it could be either as the loom rubbing is more likely to short to the transfer box whilst there is vibration present.If you can get under the car have a look yourself,it could sve you alot of dosh.The switch is just a rip off because they can,I've taken a few dead ones apart,they are not even nicely made.This is what pi--es me off with LR,its the brass neck to shaft owners with parts they KNOW are problematical.I bet they pay pennies for them.

Right, gotcha. Think I must still be a bit weak with shock!
Will get under it at the weekend and have a bit of a look.

Thanks again

MW

I saw a "pattern" WXYZ switch for aroud 130 quid from BritCar the other week but it has vanished again

Are you getting any fault codes stored in the BCU? mine regularly pops up a P0705 error code

Been under it now, found that the blue wire chafed nearly through, so I sorted that, refitted everything and it was fine for a day.
Then it did faulted a couple more times, so I gave up and went and picked up a switch today.
Of course, it has not thrown up a fault since, though I still have the INVALID in the live data.
Fault code is the P0750? Selection switch.

Not sure what to do next. I guess wait for it to fault again, then if it does fit the switch.

If not, then try and return it i guess.

Anyone able to plug in a Hawkeye and tell me what the normal live data should look like.

MW

Several days of driving later, and still it is fine.

So what do I do? Do i try and return the £350 switch? Do I continue to carry it in the car for is talisman like healing properties? DO i fit the bugger anyway while the bolts and splines underneath are still all nice and copper slipped from the last time?

Still hoping someone will share the codes / live data from their hawkeye for comparison.

MW

Mike Whiskey said:

Several days of driving later, and still it is fine.

So what do I do? Do i try and return the £350 switch? Do I continue to carry it in the car for is talisman like healing properties? DO i fit the bugger anyway while the bolts and splines underneath are still all nice and copper slipped from the last time?

Still hoping someone will share the codes / live data from their hawkeye for comparison.

MW

Click to expand...

Only just logged on after a while but thought I would let you know that I had exactly the symptoms you were describing in your first post about 18 months ago. took the bus to the stealers and they quoted some ridiculous price for a new one and fitting so ignored it for a while while I looked in to the problem.

It turned out to be dirty/corroded connectors to the switch. Got some electrical contact cleaner, cleaned the contacts in the connectors, and sprayed liberally with WD40 when finished (on the outside).

Not had a problem with the switch since then. Had other problems but the switch is fine....

Thanks Vic.

The connector block got a good clean at the same time as i was soldering up the chafed wire.

It was the two failures the following day that made me decide I'd better go and get the switch.

I wonder if i can return the switch, but keep the box so the truck 'thinks' i still have the spare. It'll never go wrong then!

MW