W639 Viano Instrument Cluster gone crazy!

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Apr 17, 2014
'95 W202 C180, '97 W208 CLK320, '06 W639 Viano, '13 GT86, '07 RX300, '09 W211 E230, '15 Jaguar XF
Hi all!

My 2006 W639 Viano LWB 2.2CDi with 62k kms on the clock has got its instrument cluster/speedometer spooked somehow.

So last week I sent the Viano for some minor detailing work (compound polish, seal and wax) as its been a while since it was last detailed. The van was just as usual, acting fine on the way home.

Next day, took the van for a drive. Was only driving for a couple of minutes when this happened - I was lightly depressing the brakes to slow down at a junction when I noticed the dash lit up with multiple warnings - ABS light, ASR traction light, ASC triangle (skid control) light, and brake pad wear warning.

All warning lights remained even after releasing brake pedal. Moreover, the speedometer was going crazy - the analog speed dial and the digital display would intermitently just jump to random speeds - say I was maintaining 80kmh then intermittently the speedo would jump to 100-120kmh for a few seconds and then goes back. Then jumps to 180-200kmh. Then back. etc.

I notice this random speedo reading happens the moment I switch on the ignition, without starting. However when in Park, only the ASC warning lights up (see pic). Once Drive is engaged, all the ASC ASR ABS and Brake Pad Wear warning will show.

Searched around for possible causes - saw some W221s with same issues which turned out to be wheel speed sensors.

Sent the car to an indy yesterday for diagnosis - came back with ABS module code :dk:. Also, Im not sure what kind of diagnosis software they were using however they managed to show me live data of wheel speeds - all wheels remained at 0kmh when the speedo showed random speeds (was stationary at that time) - this indicates its not the wheel speed sensors?

Saw a couple of 639 owners having same warning lights as a result of brake switch malfunction - however this doesnt explain the bonkers speedometer.

Any suggestions on possible causes highly welcome and very much appreciated. Tried cleaning the ABS pump connections and the engine earthing points with contact cleaner to no avail.

I'm hoping to skip the dreaded trip to the stealerships this time around - fingers crossed (just paid an arm and leg for diagnosis last month for an EGR issue).



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Something similar happened with ours which the dealer had some trouble diagnosing. Particular problem was the speedo which would fluctuate wildly. Got out one day with the engine running and it locked me out. Turned out in the end that it was the key. Got a new one and no more problems.
Hiya! :)

Thanks for your response, good Sir. That is an interesting solution you found out - will try this later with the spare remote key and see how it goes.

Reserved a slot with the stealership anyways for diagnosis next week.

(Btw apologies for not responding any sooner, just got back from a cross country work trip :rolleyes:)
Sounds like battery voltage problem, keep en eye on it, mine did a very similar thing and the next day it was flat, new MB battery cheaper than eurocarparts sorted it.
Tried the spare key, no luck - problem still there.

Also tried manually disconnecting the front ABS sensors - still no luck speedo still misreads. Might try the rear sensors next.

The van had a diagnosis appointment today but apparently the dealership had such a large backlog of benzes to repair - had to reschedule my slot next week :dk:

Voltage problem sounds like a good possibility - will look into this. The van has always broken the 25A starter fuse too, randomly, every now and again - had to stock up a few 25A spare fuses so I dont get stranded. Not sure if this might be a related issue :confused: so far van starts fine since last two weeks though - no signs of weak battery.

Hi all,

Just wanted to put a close to the story - picked up the van from stealership yesterday. They mananged to use their diagnostics machine to locate the problem to a broken wire (not really sure which one, one of the ABS wire perhaps) just underneath the front fuse box. Repaired the wiring and problem solved :bannana: *touchwood*


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