W211 e550 No Crank, No start, Full ignition
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w211 e550
W211 e550 No Crank, No start, Full ignition
I have a 2007 e550 w211 with a intermediate no crank, no start. Has full ignition, no errors in the computers, has a new starter, new crank position sensor, a new engine computer a year, new starter relay. When jumping the starter relay it fires right up. I don’t think it’s security based because I get full ignition, and I can hear the fuel pump turn on again when in the start position. My thought is a failed front sam that fails to send a start signal. What do you guys think?
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Joined: Jan 2014
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From: Republic of Texas
'99 and '05 E55 AMG
Could be as simple as a failed/intermittent relay or a bad connection. Replace the relay first.
Look for an automotive replacement fuel pump relay with the manually operated rocker on/off switch on top. Next time no crank, leave key on, pull the starter relay, insert the switched relay, then flip the switch to the on position to see if the engine turns over and starts. Once it starts, be sure to switch off or pull the relay so you do not destroy your starter!
If the engine cranks and starts, that tells you it is most likely the circuit controlling the solenoid portion of the relay. So, either an intermittent power feed, an intermittent connection to the SAM, or as you mentioned, a failing SAM
Before throwing parts at it, put it on a STAR or equivalent diagnostic system and check the front SAM and other modules thoroughly. If the SAM is failing, it should have stored failure codes.
Look for an automotive replacement fuel pump relay with the manually operated rocker on/off switch on top. Next time no crank, leave key on, pull the starter relay, insert the switched relay, then flip the switch to the on position to see if the engine turns over and starts. Once it starts, be sure to switch off or pull the relay so you do not destroy your starter!
If the engine cranks and starts, that tells you it is most likely the circuit controlling the solenoid portion of the relay. So, either an intermittent power feed, an intermittent connection to the SAM, or as you mentioned, a failing SAM
Before throwing parts at it, put it on a STAR or equivalent diagnostic system and check the front SAM and other modules thoroughly. If the SAM is failing, it should have stored failure codes.
Thread Starter
Newbie
Joined: Oct 2020
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w211 e550
Could be as simple as a failed/intermittent relay or a bad connection. Replace the relay first.
Look for an automotive replacement fuel pump relay with the manually operated rocker on/off switch on top. Next time no crank, leave key on, pull the starter relay, insert the switched relay, then flip the switch to the on position to see if the engine turns over and starts. Once it starts, be sure to switch off or pull the relay so you do not destroy your starter!
If the engine cranks and starts, that tells you it is most likely the circuit controlling the solenoid portion of the relay. So, either an intermittent power feed, an intermittent connection to the SAM, or as you mentioned, a failing SAM
Before throwing parts at it, put it on a STAR or equivalent diagnostic system and check the front SAM and other modules thoroughly. If the SAM is failing, it should have stored failure codes.
Look for an automotive replacement fuel pump relay with the manually operated rocker on/off switch on top. Next time no crank, leave key on, pull the starter relay, insert the switched relay, then flip the switch to the on position to see if the engine turns over and starts. Once it starts, be sure to switch off or pull the relay so you do not destroy your starter!
If the engine cranks and starts, that tells you it is most likely the circuit controlling the solenoid portion of the relay. So, either an intermittent power feed, an intermittent connection to the SAM, or as you mentioned, a failing SAM
Before throwing parts at it, put it on a STAR or equivalent diagnostic system and check the front SAM and other modules thoroughly. If the SAM is failing, it should have stored failure codes.
It starts fine with a jumped relay, the relay is brand new but not being actuated by the Sam. I can tell the the key start position is working because the pump turns on whenever you turn to the on position and it will turn on again after that once you turn into the start position.
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Joined: Feb 2007
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From: Republic of Texas
W203 W212 W211 R53MCS
So the starter relay is located in the front SAM but it is the engine module that sends the ground signal to turn the relay on. Did you install a new engine module from the dealer or a used one???
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w211 e550
It was a remanufactured that had my vin/ serial burned into it or they repaired my old ecu... the company in which did the work was vague on what they did however they have a warranty and it will only cost me a few bucks to have it tested. I suppose I should send it off and let them have at it so worst case scenario I know that it’s a known good.
Thank you for the information on the start signal coming from the ecu to fire the relay. Helps narrow it down a bit!
