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No crank, no start, can I get the wiring diagram for the ECM?

Tiny
HAL1958
  • MEMBER
  • 2009 MERCEDES BENZ CLK 350
  • 3.5L
  • V6
  • 2WD
  • AUTOMATIC
  • 128,000 MILES
Engine ECM is not communicating with scanner. All other modules show on scanner. No voltage at starter relay. ECM was sent out and found software failure and corrected and reinstalled. Front sam check good on scanner. New battery installed. All fuses and relays check good. Need wire diagram for ECM connectors and what pins to check voltage. Thinking ECM is not getting voltage input.
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Wednesday, March 13th, 2024 AT 12:37 PM

33 Replies

Tiny
BORIS K
  • MECHANIC
  • 762 POSTS
Hello,

On the ECM you have 2 connectors.

C1 - 96 pin
C2 - 58 pin

Pin out at connector C2.

Pin 3, red/blue wire ignition 12V from fuse F53(15A) in front SAM
Pin 5, red/blue wire ignition 12V from fuse F53(15A) in front SAM
Pin 16, red wire constant 12V from fuse F57(5A) in front SAM

Also check your grounds at pins 2, 4, 6, brown/white wires.

Diagnostic wire, blue/yellow, comes from pin 29 to OBD connector pin 7.

See image below for 12V and ground wires.

Cheers, Boris
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Thursday, March 14th, 2024 AT 4:08 AM
Tiny
HAL1958
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I’m assuming these tests are done with ECM removed. If so, I removed ECM and check pin 16 and has 12v constant. Pin 3 and 5 have no volts and fuse 53 no volts with key on position. Pins 2, 4, 6 have good ground. Pin 29 to pin 7 is good ohms. I replaced relays for circuit 15 and 87, still the same.
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Thursday, March 14th, 2024 AT 6:24 AM
Tiny
BORIS K
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Hello,

The ECM needs to be plugged in to activate the engine circuit relay 87, if ECM unplugged fuse F53 will not be energized.

ECM on connector C2 pin 27 outputs a ground on brown wire to front SAM pin 8, connector C2. This in turn will switch relay to output 12V to fuse F53.

Also fuse F53 needs to be live to energize the starter relay, see image below.
I had to separate wiring diagram for display purposes.

Cheers, Boris
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Thursday, March 14th, 2024 AT 7:08 AM
Tiny
HAL1958
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I reinstalled ECM. With key on position, fuse 53 still has no volts.
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Thursday, March 14th, 2024 AT 8:45 AM
Tiny
HAL1958
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Also, do I need to have someone in the car to turn the key to the start position to have voltage present at fuse 53? I only had key in the on position for dash lights to come on.
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Thursday, March 14th, 2024 AT 9:35 AM
Tiny
BORIS K
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Hello,

As fuse F53 is supplied by relay 87 you will only require the ignition to be on.
Suggest checking that the ECM switches a ground out at pin 27 to the front SAM at pin 8, connector C2.

See image below.

Cheers, Boris
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Thursday, March 14th, 2024 AT 10:20 AM
Tiny
HAL1958
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Do I back probe pin 27 at ECM ohms to ground? Also, which 87 relay am I checking? Chassis- N10/1kl or engine- N10/1ks?
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Thursday, March 14th, 2024 AT 3:09 PM
Tiny
BORIS K
  • MECHANIC
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Hello,

You are checking engine87 relay in front SAM.
You could back probe pin 27 to check if ECM is switching ground out, better still check that ECM is switching ground out at the relay socket, terminal 85.

Cheers, Boris
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Friday, March 15th, 2024 AT 4:10 AM
Tiny
HAL1958
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I removed engine 87 relay. Then I installed a wire in socket term 85. I put the key in the on position. Then I connected my ohmmeter to wire and then to ground and it shows no ground. Will it still show a ground with relay removed?
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Friday, March 15th, 2024 AT 8:07 AM
Tiny
BORIS K
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Hello,

It will as the ECM pulls a ground through terminal 85 via brown wire to ECM pin 27.
As you are not getting a ground you either have a connection issue inside the front SAM from terminal 85 to pin 8, a possible broken brown wire to ECM or an issue inside the ECM.

Suggest checking each circuit separately, front SAM and brown wire back to ECM.

Cheers, Boris
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Friday, March 15th, 2024 AT 9:11 AM
Tiny
HAL1958
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I checked for continuity between ECM pin 27 and term 85 was good. So brown wire is okay. Can I bypass that ground? Splice a wire to the brown wire and connect to chassis ground? Also, are you saying that fuse 53 will not get power unless pin 27 grounds? Is there something I can check with my scanner?
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Saturday, March 16th, 2024 AT 7:06 AM
Tiny
BORIS K
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Hello,

The relay needs to switch to supply fuse F53. You could try and supply a separate ground to the relay and see if it will switch.
Keep in mind that if the ECM does not switch a ground out this could point to an issue inside the ECM.

Cheers, Boris
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Monday, March 18th, 2024 AT 10:31 AM
Tiny
HAL1958
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How can I check if the ECM is getting power from battery? When the ignition switch is on what pin on the ECM should read 12v? Also, I read that the electrolytic capacitor 200uf 50v is a common problem on this Bosch me9.7 ECM. How can I check it to see if this is the power supply problem that I’m having?
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Monday, March 18th, 2024 AT 11:48 AM
Tiny
BORIS K
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Hello,

On ECM connector C2.

Pin 15, pink/red wire 12V ignition from front SAM pin 12, connector C2.
Pin 16, red wire constant 12V from front SAM pin 4, connector C2, fuse F57(5A).

On diagram terminal 15 is ignition, 30 is constant 12V, 31 is ground.
See image below.

Cheers, Boris
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Wednesday, March 20th, 2024 AT 10:03 AM
Tiny
HAL1958
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Pin 15 has 12v with ignition on, and 0v with ignition off. Pin 16 has constant 12v also at fuse 57. I opened the ECM and removed capacitor and will order part to see if that fixes the power problem before replacing ECM. In the meantime, there is another problem. A buzzing sound near the center of engine that drains my battery overnight. It's not from the relays in the front sam. The only fuse that stops it is fuse 55. What does fuse 55 control that would make this buzzing sound so I can replace the part?
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Sunday, March 24th, 2024 AT 6:09 AM
Tiny
BORIS K
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Hello,

Fuse 55 in front SAM controls several different outputs.
See illustrations below.

Picture 3 shows description and front SAM connector and pin description.
Connector 21 and 9, as illustrated in image 1.

Cheers, Boris
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Monday, March 25th, 2024 AT 2:07 AM
Tiny
HAL1958
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Hello, I replaced the 220uf 50v capacitor in ECM. Now when I remove the starter relay and jumper it the car will crank but no start. Before it would not do that. If I try and use the key to start I get no crank. Also, I don’t hear the fuel pump. I replaced the fuel pump relay and fuse in trunk still the same. What else can I check now? Thanks.
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Tuesday, April 2nd, 2024 AT 7:35 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,942 POSTS
Lets run the codes to see if any are stored.

This guide can help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Also, does the security light flash when the engine is cranking? If so, the system is enabled and needs to be reset.
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Friday, April 5th, 2024 AT 9:03 AM
Tiny
HAL1958
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When I jumper starter relay the engine cranks, but no start and security light does not flash. Immobilizer is ok. With key in on position fuse 53 has no volts so how come engine cranks with jumper if no power at f53? I thought f53 needs power to crank? Also, I cleared codes and still has no communication with ECM and dtr and has a lot of codes for ESP and TCM. Also front SAM showing code B1036. Enclosed codes below.
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Saturday, April 6th, 2024 AT 7:54 AM
Tiny
HAL1958
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ECM.
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Saturday, April 6th, 2024 AT 7:55 AM

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