Flashing Instrument Panel on ignition pos 2?

[LeaUK]

Here's a weird one that happened tonight - although only briefly.

Switched to ignition pos 2 so that all the lamps in the IC illuminated, then after around 30 seconds they all started erratically flashing with the car making horrible electro-mechanical sounds (relays, pumps, engine components) in time with the flashing. I ran back from beneath the bonnet and switched off.

My immediate reaction was to blame the battery as it's now two years old and many of my journeys are rather short, so got the charger out and switched on. BUT I was shocked to see only minimal current draw - it's not the battery!

So off to investigate....

Switched to pos 2 to attempt to locate the poor connection, lots of flashing again so went straight to the fuse box and started 'wiggling' - no difference. IC still flashing irregularly! Wiggled the battery terminals (as much as you can) nope...

Moved the steering wheel up/down/in/out to check it wasn't the ignition barrel - no difference..

Ironically, in pos 2 with the IC panel now all dark (stopped flashing) I moved to position 3 - the car started instantly....how weird is that! No IC but the car starts?? and of course, the WORST thing that can happen to intermittent faults - now I can't get the IC to repeat any of the symptoms encountered just previous .... arrrg!


My first thoughts are with the immobiliser as this directly disables the ignition and the IC panel from illuminating (amongst other things) - maybe carboned relay contacts?


Onto the obvious - has anyone else seen similar?

Cheers
Lea

[LeaUK]

A quick update, turns out to be the ignition switch so I've ordered a new switch and tumbler - it's a two part assembly. Cost around 140GBP.

BTW - I first looked at the ignition immobiliser and bearing in mind it was fitted by 'qualified and authorised' insurance alarm fitters found two chassis ring terminal connections where the fitters didn't bother scraping the paint first So I'm surprised it actually worked in the first place!

Turns out this wasn't the cause though and was definitely due to the switch. If I carefully turned the switch to ignition then backed it off fractionally I could reproduce the flashing IC panel. I also noted that the positions were not as defined they should feel so hence the reason for purchasing both barrel and switch.

Now simply waiting for the matched barrel to arrive from Germany

For the reference of others here's the removal video: http://www.mbca.org/northtexas/repair_videos.htm

Lea

[Hans]

LeaUK - Thanks! My tumbler will not turn to position 1. Do you know anyone that has cut one of these things apart???

[LeaUK]

Hi Hans

Sorry mate, nope. Thankfully mines mechanically ok so I haven't investigated your issue. If I were you I would make a post on the Tech Help forum as the barrel is probably a common part for many Benz's.

Cheers and Happy New Year.
Lea

[LeaUK]

So here's an 'interesting thing'! Have replaced my ignition switch see here but today I notice that when I hit the start position 3 - bang, flashing IC lamps again!!!

OK, this time it must be the battery causing excessive voltage drop as the starter begins to turn. The initial current from starters under locked start condition is HUGE and so the voltage dips significantly. If your battery's a little tired then this drop is very significant and subsequently shutdown of all electronic modules is inevitable - the IC lamps extinguish.

When the volts fall below the operating point of the solenoid the starter stops pulling current and the volts begin to rise again, momentarily causing the IC to illuminate. Subsequently the solenoid clicks back in causing the starter to pull huge current again - then the whole oscillation process begins.


Today I find my bat is 9V just in position 2 with the IC on!!!

Here's some short video of the oscillation you may experience when you have battery issues or of course when the ignition switch fails and causes a similar poor connection.

Oscillation Video

[GregE240]

Lea,

I had EXACTLY the same symptoms a couple of weeks ago when my battery gave up the ghost.

I had left the car for 3 weeks whilst we were on holiday and had the same problem. A quick call to my mechanic confirmed that I could jmp start the car provided no electrics were on, just the starter and I got her going. A short drive later and all appeared happy again. However, several days later the battery was flat again.

I thought I'd try another battery over the Mercedes OEM fitted, so a trip to Halfords (UK motor factors) and we were up and running again. This battery has a slightly higher cold crank rating to the OEM, so fingers crossed.

I've also invested in a solar powered trickle charger.

Greg