Mercedes-Benz Forum banner

21 - 28 of 28 Posts

·
Registered
1983-2007 MB's
Joined
·
8,015 Posts
Replaced the ignition coil (I cleaned but did not yet replace fuel pump relay and other obvious and easy checks (fuses).
You really should check if you've got fuel or spark present before digging further. If no fuel, jumper the relay at pins 7 and 8, try starting with module pulled off.
 

·
Moderator
1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
Joined
·
4,035 Posts
gogi is right.

I am unsure how you would modify the front crank position sensor to match the rear really. The EZL has but two connections via that coax cable plug.

The rear one on my '91 Euro 500SEC had diagnosed as intermittently bad early last Summer.
It was replaced at my MB dealership and during the repair, the fuel pump relay was dissected as well, and a couple of toasted solder joints were discovered.
Rear crank position sensor replaced, FP Relay was replaced too... [aftermarket one].
During the ensuing weeks, the Original FP relay resoldered/re-installed.
The car is totally reliable now.

* It is not clear to me still, if the rear crank position/speed sensor actually was the engine compartment temperature-related problem.

M

Sorry about the image clarity there.

This shows the plug to the EZL.....
 

Attachments

·
Registered
Joined
·
50 Posts
Right. I thought of that. By extend the cable you literally rebuild it with a longer Coaxial cable? Get that extra foot of length by "splicing it in?" As to the metal piece, just fuggettaboutit?
 

·
Registered
Joined
·
50 Posts
2613007
I'm quite sure this is the part on my 560 SEL, 1988 (which also fits the 420)/ Wells has discontinued it. Who knows how to find this? Or, even better, who has one willing to part with it. Thanks, D Day, maine
 

·
Moderator
1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
Joined
·
4,035 Posts
That is surely the rear crank position sensor for your car...

I tested the impedence of the CPS on mine numerous times with different engine temperatures as part of my diagnosis process.
Is yours open circuit? Shorted?

Sorry to sound like a broken record here, but given my experience last summer, are you sure that the fuel pump is 100% bad?

M
 

·
Registered
Joined
·
50 Posts
Thanks, MBL. I'm going to tow the car to the Guy Who Knows. I may ask him to let me look over his shoulder during all the tests to determine the answer to Open Circuit, Shorted, etc. Will let you know. Doug
 
21 - 28 of 28 Posts
Top