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Discussion Starter #1 (Edited)
Hey comrades..

I bought a 1996 C280 last week with only 184 000km! It had only two owners from new, and came with all the books + Service history :)

Got it for a good price and everything seemed perfect during the purchase.. only thing that was not working is the temp gauge, and the SRS light was on. and I thought it came with 3/4 tank of gas lol..

Later that night I took the car for a drive, and as I started it multiple warning lights lit up, aswell as the handbrake light (with the handbrake off). At this point the speedo dies.. Later the next day it worked ok for five minutes untill the problem returned. Its been on and off ever since, but more off than on..

The fuel gauge deceived me and ran out of gas while it still showed half a tank. though it did go down gradually as I drove untill the halfway point where the gas ran out.. SO the "half a tank" point is equivelent to empty tank lol.. took me braking down twice to figure that one out lol..

SO I thought, "ok, must be a faulty cluster".. so while I was getting a windscreen for the car at the breakers, i found a lovely 130k cluster from the same C280 elegance I was removing the windscreen.. got the cluster for only $90 :D

popped the replacement cluster into the car, started it up but the EXACT same symptoms showed instantly :( so we can eliminate the cluster entirely from this equation, right?

I returned the cluster the next business day, and now I am trying to track down the REAL cause to the problems..

Which module / computer sends the signals TO THE instrument cluster?
 

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Hey comrades..

I bought a 1996 C280 last week with only 184 000km! It had only two owners from new, and came with all the books + Service history :)

Got it for a good price and everything seemed perfect during the purchase.. only thing that was not working is the temp gauge, and the SRS light was on. and I thought it came with 3/4 tank of gas lol..

Later that night I took the car for a drive, and as I started it multiple warning lights lit up, aswell as the handbrake light (with the handbrake off). At this point the speedo dies.. Later the next day it worked ok for five minutes untill the problem returned. Its been on and off ever since, but more off than on..

The fuel gauge deceived me and ran out of gas while it still showed half a tank. though it did go down gradually as I drove untill the halfway point where the gas ran out.. SO the "half a tank" point is equivelent to empty tank lol.. took me braking down twice to figure that one out lol..

SO I thought, "ok, must be a faulty cluster".. so while I was getting a windscreen for the car at the breakers, i found a lovely 130k cluster from the same C280 elegance I was removing the windscreen.. got the cluster for only $90 :D

popped the replacement cluster into the car, started it up but the EXACT same symptoms showed instantly :( so we can eliminate the cluster entirely from this equation, right?

I returned the cluster the next business day, and now I am trying to track down the REAL cause to the problems..

Which module / computer sends the signals TO THE instrument cluster?
Alternator or ground short to chassis.

Only way hand brake light can come on, is if there is a major backfeed of power.

I would take the back board off of the gas tank and look at the tank.

You could just unplug the charge wire off of the back of the Alt. That would tell you alot when you started it again.

Might want to Ohm all of the fuses again. My bet is you popped one or two. Better take the K-40 apart and look at it too. Before its too late.
 

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Discussion Starter #3
Alternator or ground short to chassis.

Only way hand brake light can come on, is if there is a major backfeed of power.

I would take the back board off of the gas tank and look at the tank.

You could just unplug the charge wire off of the back of the Alt. That would tell you alot when you started it again.

Might want to Ohm all of the fuses again. My bet is you popped one or two. Better take the K-40 apart and look at it too. Before its too late.
Thanks MM!

Il check all the fuses again tomorow. also will check the grounding wires behind the cluster itself. (From what I have read from searching this forum)

Where is the K-40 located on the W202?

Il also check out the alternator. You say disconnect the "charge wire?"
 

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Thanks MM!

Il check all the fuses again tomorow. also will check the grounding wires behind the cluster itself. (From what I have read from searching this forum)

Where is the K-40 located on the W202?

Il also check out the alternator. You say disconnect the "charge wire?"
Yes the big FAT one, wrap the disconnected end in tape though.

Let me go snap a picture of a k-40 for you.
 

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Picture sent to your phone.

 

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Discussion Starter #7
Thanks again MM..

I did reply, maybe u did not receive it..

Is that relay located in the trunk? On the right hand side next to the spare wheel and battery? I think that's where I seen this relay..

Daylight has arrived. So I can go investigate this matter further..

Thanks for the pointers..

Any other things I can check while I'm at it?
 

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Discussion Starter #9
Ok thanks my friend :)

Will report back with my findings
 

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Ok thanks my friend :)

Will report back with my findings
I got the chat open over there. be there for a few hours, look me up.


I getting another pic for you too hold on.
 

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Check all these terminals, not just the ones with arrows, but all.


What your looking for is dis-coloration of the metal on the terminals.

And if any of the wiring does not come out when you release the clips, it might be because it melted the plastic around the terminal area, making it stick.
 

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Discussion Starter #12
Unfortunately I'm using my fone, so I won't be able to log on that side for now.. (Chat does not work on mobile)

So I've looked all over, checked all the ground wires, everything was fine..

Checked the cluster (just in case) and it too was flawless, no burnt resistors..

Just still can't find this k-40 relay!!! Lol, looked all over! Do u have a pic of where it locate on a W202?
 

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Discussion Starter #13
Could a faulty speed sensor cause this?

Also I replaced the temp sensor this morning, still no temp reading on the cluster :(
 

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Go back and read post #8 again.
 

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Discussion Starter #15
I looked everywhere!!! Believe me its not there my friend.. (I tried to upload a pic of that area, but my Blackberry keeps crashing)

Is it possible that the K-40 was combined with the LH module? I just stumbled across something interesting, probably the root cause..

My LH module part numbers are:
202 545 44 32
It also has the letters K-40 printed on the side with the part number..

Now when I scan it with my Carsoft 7.4 this is what comes up:

Single Dianosis LH - Staus Error

Module info: LH
MB - Nr: 022 =34 12 38
Supplier: Bosch
Hardware version: 56/52
Software version: 10/30
Diagnosis recogn: 00/11
Engine size: 0,7l
Program version: 05
Data version: 04

Lh_feh.dxt

17 Fault in CAN communication with EFP control unit

While IGNITION OFF, unplug coupling at EFP control unit and test with ohmmeter directly at coupling. Resistance = 115-125 ohm. Or EZL ignition control unit is not transmitting.


3 Coolant temp sensor: sensor circuit 2 open circuit / short circuit.

Verify coolant temp sensor voltage at sensor circuit 2.
20'c = 3,5v =2500 ohm.

- single diagnosis completed.




Noiw before we even look at the errors, what draws my attention is the incorrect information about the module itself..

The "MB number" or part number is totaly wrong and even contains a "="

It says the engine size is "0,7l"????

And the hardware / software versions don't seem correct..

So what do you think mm? My LH module on this car is kaput? I'm almost sure that this is the culprit, because on all my other scans I have never seen this before..

The module build date is 28 / 11 / 1995.. So I guess they interchangeable without needing re-programming?

If you concur with my thoughts about this, I can quickly take a ride to my local breakers and pick a replacement module for about $50 if they have the right one. (I'm quite sure they do)

What's your thoughts on this?
 

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My 10 cents, change the LH control unit.
 

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Discussion Starter #17
**UPDATE**

Ok so today I went ahead got a replacement module.. Cost me bit more than I thought, but if it fixed the probs it would be worth it.

Disconnected the battery, unplugged the old "faulty" module and replaced it with a module from a really low milage donor vehicle..

Reconnected everything properly, and went to start the car.

Started up perfectly (as it did before) BUT.. The cluster issue was still there!!!! Speedo not working, fuel gauge misleading and temp gauge not working..

Car drives fine though.

I wanted to hook the Carsoft up to the car again just to erase any errors and verify that the module is connecting to the car properly.

Started to rain, and rain hard.. Will have to perform further tests tomorow during the day, if the rains don't prevent the progress..

Upon initial tests, the problem is there.. So far I tried replacing:

- Instrument cluster
- LH computer module (part number 202 545 44 32)

Also I checked all the ground cables and connections which all seemed solid.

Mercedes Mechanic, did u get a pic of where the K-40 relay is located on a W202? I looked hard at the breakers and could not find that part :( maybe it is in deed a major culprit in this case?

Pics to come later..
 

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Mercedes Mechanic, did u get a pic of where the K-40 relay is located on a W202? I looked hard at the breakers and could not find that part
It has a OVR not a k-40, I didnt look at the year.
 

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Discussion Starter #19
its understandable...

So where do I go from here? What's the next place I should look to solve this prob?

Cluster - fine
LH computer module - fine


Could it really be the invidual sensors? Speed sensor, fuel level and temp sensor?

I disproved that theory by replacing the temp sensor and still no reflection on the gauge.

So I'm left standing just scratching my head lol.. Still gotta do that diag and memory erase tomorow, but after that I have no plan yet to go forward and solve this issue..

What's the next step?
 

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So I'm left standing just scratching my head lol.. Still gotta do that diag and memory erase tomorow, but after that I have no plan yet to go forward and solve this issue..

What's the next step?
On the fuel gauge issue, did you check to make sure your tank is not caved in?




I KNOW YOU checked all the connectors. I would say that the temp guage is caused by faulty wiring, but let me go check the diagrams.

Be right back.
 
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