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  #1  
Old 01-16-2003, 09:04 AM
Potomac German Auto
 
Join Date: Mar 2002
Location: Frederick, MD
Posts: 407
Thumbs up Coolant temp sensor (CIS/EZL)

I think I may have finally figured out what is plaguing my car.

I was working on the 16-vlv last night down @ RC Imports & was trying to troubleshoot where my power loss & sporadic start problem are coming from.

Here's my question. On the coolant temp sensor for the 16-vlv has two leads. When the leads are pulled during idle the car should stumble & the idle should act weird.

When I pull mine the idle stays constant. I looked at the schematics for these leads. Both green wires, one w/ a red trace & the other black. Apparently there are four (X48) diodes soldered in somewhere on these wires. I am assuning that one is the R/16 and the other three I am unsure of...

With a failed diode in line would it be possible to be getting feedback through the diode which in turn would cause incorrect signals to each unit?

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1994 E500 (MY SUNDAY DRIVER)
1993 190E SPORTLINE LE W/ M104 SWAP
1997 C230
2002 ML320
2000 BMW 528I (WIFEY'S CAR)

"Excuses are crutches for the unfounded."
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  #2  
Old 01-16-2003, 10:12 AM
Registered User
 
Join Date: Aug 2002
Location: Central Asia
Posts: 104
coolant temp sensor

Hello Potomac Pat,

I am glad there is someone in the world who also thinks that a bad temp sensor input is causing problems to the car.
My car 1989 230E has 2.3 liter 8v engine. It idles at 800 rpm when the ingine is hot or cold. I think that the car should idle at higher speeds when cold. Disconnecting the temp sensor should change the engine's speed. My car does nothing when I disconnect the 4 pin temp sensor. I have posted it's picture. The temp sensor is part #1 in the following link.
1 engine, 3 temp sensors?
If you can read the schematic you can look at the KE Jetronic system's detailed schematic below. It will take you 20 seconds to download this with a modem. Don't ask me if I can read the schematic for you because I don't understand !@#$ in this.

http://www.autolib.diakom.ru:8001/CARS2/main/Mercedes-Benz/shematic/controller/KE-Jetronic/mke.pdf

Hurshi
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1989 230E, 8v, 166.000 km, updated to 94/95 trunk & hood
2002 Daewoo Nexia 50.000 km
Sold:
1987 VW Jetta GLE 16V, Recaro seats
1982 Volvo 240 DL (lovely car!)
and few more american cars.
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  #3  
Old 01-16-2003, 12:04 PM
Potomac German Auto
 
Join Date: Mar 2002
Location: Frederick, MD
Posts: 407
I don't know which 4-pin connector you are talking about?

The coolant temp sensor on the 16-vlv is a two pin connnector. I changed all of the sensors on my head two weeks ago w/ new parts.
I can read the schematics, but I am wondering if the feedback through a failed diode would screw w/ the CIS/EZL signals during normal operation !!!
__________________
1994 E500 (MY SUNDAY DRIVER)
1993 190E SPORTLINE LE W/ M104 SWAP
1997 C230
2002 ML320
2000 BMW 528I (WIFEY'S CAR)

"Excuses are crutches for the unfounded."
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  #4  
Old 01-16-2003, 06:25 PM
ILUVMILS's Avatar
Senior Member
 
Join Date: Sep 2002
Posts: 3,066
Pat, why do you say the engine should stumble and so forth when the temp sensor is dis-connected? True, the fuel mixture depends on coolant temp as well as several other inputs, but when you dis-connect it, the CIS-E control module enters a fixed mode to maintain driveability. I'm not sure about the diodes you mentioned either. If I have time I'll look at the wiring diagram at work tomorrow.
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  #5  
Old 01-16-2003, 06:32 PM
yal's Avatar
yal yal is offline
Benz-smart
 
Join Date: Oct 1999
Location: New York, Long Island
Posts: 2,707
I agree this is probably normal. Pulling the lead does nothing. Nothing happens on my 2.3 either. The EHA on the other hand, mess with that and and the idle goes to hell.

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