speedtronic inoperative and wroing speed

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Stuckmojo
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Hi, 

I just picked up the G55 from the mechanic after a gearbox oil change. Car runs well but now i have this "speedtronic inoperative" message as well as having the wrong speed in the digital dial. It shows KMh - the car is a lhd, and over-reads by 2x. 


I used to be able to switch it to miles but now I can't. (edit, the odometer changes, but the speedometer stays in km/h)


I know the mechanic was fiddling with his star system to look at deleting the "foglight" error as my car has them removed. I wonder what's gone wrong there. 

Thoughts? 

Car is a 2008 G55K

Arnie
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Re: speedtronic inoperative and wroing speed

Does your transfer case still operate? Do all gearbox functions work OK? Do you have an ESP warning ? Have you changed your wheel/tyre combination?


I wonder if your mechanic has version recoded some function of the gearbox or even updated its software? 

All you need to do on STAR to change the gearbox oil is to read the temperature of the oil, as its density and hence level depend on temperature. Just monitor oil temp and no need to reprogramme anything.

Perhaps you need to ask your mechanic exact;y whet he did and see if he is prepared to pick up the cost of you taking it to MB to have whatever it is recoded.

The speedometer gets its reading from one of the ABS wheel sensors and this is cross-referenced to another speed  sensor in the gearbox. The two are used by ESP to detect wheel slip. There may also be a link with the transfer case, selection, which may explain a x2 error.

If nothing has been re-programmed, then go back to your mechanic and ask that he carefully checks all electrical connectors to the gearbox.

The electrical connector to the 5-speed gearbox was subject to a recall for allowing oil leakage through the connector and then up the cable-sheath and into the electronic control unit, thereby causing problems. You may just wish to check this, though not all connectors had this issue and probably not on late-model ones like yours.

 

 

 

Arnie
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Re: speedtronic inoperative and wroing speed

I suspect that the answer lies here somewhere if perhaps your mechanic has been busy intentionally or unintentionally recoding:

http://www.pointedthree.com/disc/forums/showthread.php?tid=9622&posts=54&mid=107881&action=search

 

Stuckmojo
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Re: speedtronic inoperative and wroing speed

Thanks both. Car goes back today. He emailed me yesterday to tell me he knows what's happened and he'll need 1 hour for this. 


The car has the G63 tyre/wheel combo - 20 inch. Though it had it since I bought it and the reading was always dead on. Nothing changed there. 

I'll ask to check the ABS sensor, wheel speed sensor and gearbox sensor too. He did fiddle with the instrument cluster so that's the issue in my mind. 

I'll keep you updated. 


With new oil the gearbox works a million times better. 

Stuckmojo
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Re: speedtronic inoperative and wroing speed

I haven't taken the car back yet, will do on Tuesday (work travel). 

In general, who are the ninjas of diagnostics and electrical bits? My CEL light is still on with that annoying O2 sensor error - It's either the ECU or the loom, this has been established. 

Local MB dealer is known for being useless (I can confirm with the fact that they made me the wrong key for the car, 1st strike)

Arnie
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Re: speedtronic inoperative and wroing speed

 

step-0:

Get hold of a copy of WIS (eBay) , install on a laptop or PC and after entering your VIN, print out all the wiring diagrams for the ECU and its sensor connections. this will give you the wire colours and identification.

step-1:

check the fault codes stored on the ECU to verify which area the fault may be in. (O2 sensors?)

step-2:

Eliminate wiring faults by buzzing through all the wires individually from sensor to ECU. (use a multimeter, and yes, it will take time)

step-3:

If it's the ECU, you can try some company such BBA Reman. However, many such enterprises may only be competent at fixing common ECU faults, like bad capacitors. My guess is that an ECU fault is unlikely.


Step-4:

The apparent fault may actually be as a result of something else in the same chain (fuel-system, mixture preparation etc), so consider other factors. Also, you need a STAR or XENTRY diagnostic to get the precise error code as most scanners only give you generic decoding, which may not be applicable to you G. Check that the error is repeatable after clearing the fault.

 

Stuckmojo
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Re: speedtronic inoperative and wroing speed

Thanks Arnie.

Just my luck, the starter motor died while at the mechanic. Car is still there until tomorrow, then he'll take it to MB next week to his friend the service manager to run a full diagnostic there and try to sort the issue. 

Let's see what happens then. 

 

Arnie
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Re: speedtronic inoperative and wroing speed

Are you sure it's the starter motor and not perhaps the battery or stuck solenoid?

Good luck anyway !

Stuckmojo
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Re: speedtronic inoperative and wroing speed

Arnie wrote:

Are you sure it's the starter motor and not perhaps the battery or stuck solenoid?

Good luck anyway !

We put in a new battery and put the car on the ramp./ I was there. 3 mechanic were all adamant it was the starter motor as the solenoid was alive. Yes, good luck to me!

Stuckmojo
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Re: speedtronic inoperative and wroing speed

Quick update - the starter motor had indeed given up the ghost. Spins up very rapidly and works well now. 

 

Next week full diag at Mercedes. I want these electrical gremlins gone. Car runs perfectly otherwise - Amazingly, it tuned to UK TV by itself!