[mathiasviva]

Hi
First of all, I am new to this forum. I have used it as a library for a long time but signed up as I need help from more experienced R129 owners.
My car is a 1993 600 SL and I have slowly fixed most issues with it.
Today I was looking for the problem with the high speed AUX fan not kicking in, and as a step I short circuit the two pin temp sensor on top of the termostat housing with a screw driver. However, in the process i accidently touched the thermostat housing with the screwdriver, creating a short circuit between the temp sensor connector pins and ground.
This created a small spark.
Unfortunately this broke something. After assemby the engine had problems starting and when it did start it was running very poorly, the ASR light came on, and the tach gauge is not working.

I tried all the basic things; went through all the fuses, disconnected the battery for 10 min, removed and reconnected most connectors under the hood. No change.
I then did a fault code check and discovered that pin 4 and 17 seems to have a short circuit. The LED is lit up all the time. Since pin 17 is related to the EZL i tried disconnecting them one by one.

After disconnecting the EZL in the front, the car would not start at all. After reconnecting it and disconnecting the "rear" EZL the car behaved exactly the sames as with the EZL connected.
My conclusion is that the rear EZL is fried.

What do you guys think? Are there any other tests that I can perform? Are there any fuse inside the EZL that can be changed? Could more modules have been damaged?

 

[mathiasviva]

I might add that the engine wiring harness is recently changed and the engine was running perfectly before i short circuit the temp sensor connector.

 

[roncallo]

Code says pin 4 and 17 have a short. Check those pins for a short before changing an ELZ. Short to each other and short to grounds. Check at the ELZ and at the far end of the wire harness and anything that harness connects to. Check the pins on the other ELZ and its harness to see if they react differently. Are both ELZ's the same part number and can they be swaped?

 

[bobterry99]

Today I was looking for the problem with the high speed AUX fan not kicking in, and as a step I short circuit the two pin temp sensor on top of the termostat housing with a screw driver.

On some systems this will not cause the fans to run, because the climate control unit regards the zero-resistance input from the screwdriver as a fault. A resistor with a value of around 100 ohms placed between the connector terminals should always works, however.

After assemby the engine had problems starting and when it did start it was running very poorly, the ASR light came on, and the tach gauge is not working.

You likely blew one of the fuses installed atop your Base module. The Base module is located in the engine compartment among the fuel injection and ASR controllers.

 

[mathiasviva]

Thank you bobterry. You have saved my day!
It was one of the fuses in the main controller that had blown. Pin 4 and 17 now gives no errors and engine is running perfectly!
Thanks for the tip on the resistor as well. I will try it.