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Was driving the car in the morning for about 5 mins when I lost power. Looked at the instrument cluster to see
1. Coolant temperature too high warning message with temperature light in red colour
2. No visible bars in the temp gauge cluster
Stopped the car switched off and switched on and car didn't crank
3. Radiator fan started running at full speed until I switched off the key
checked random fuses, wiggled them and wiggled the relays of the front SAM. No difference. Tried to scan the car using a basic bluetooth adaptor which I usually use to read fault codes. It didn't get connected (fried SAM or ECU?). Call me it's a placebo effect but I smelled something funny under drivers floor but didn't inspect anything.
Car is now at workshop waiting for diagnosis. Any suggestions for me to advise the guys to look into rather than replace SAM or ECU
No crank + full speed fan... that's pretty extreme 😳
1- check the data value for your COOLANT TEMP!
2- then physically inspect the sensor connector pins
3- then look over data again for any change
With engine cold you expect near ambient temp +/- 15%
W211 270CDI 2003
Temperature was fine when I read it with computer. Sensor pins looks also good.
ECU have been tested and there was no problem. Also starter seems to be fine because i can get it crank with jumping starter relay.
W211 270CDI 2003
Temperature was fine when I read it with computer. Sensor pins looks also good.
ECU have been tested and there was no problem. Also starter seems to be fine because i can get it crank with jumping starter relay.
Hi All, as this is a very old thread, I thought it might still be interesting because just had this issue.
With thanks to all who have replied to this before, Suspecting Temperature sensor and ECU goes way too far.
I had the exact same symptoms on my 2004 W209 with M112 (240) . All light come on when turning the key (except Water Temperature which remains 0 or blank) and few seconds later the Radiator Fan goes on full speed.
It turned out to be from the start enable relay (I read here that someone called it K40). It is one of the black relays on the front SAM. Marked with Red Cross in my photo.
I opened the casing of the relay and pushed it by hand and Voila everything worked.
Just to make sure I swapped the two black relays and the symptoms changed. So, that was our bad guy.
Hope it helps.
Hi All, as this is a very old thread, I thought it might still be interesting because just had this issue.
With thanks to all who have replied to this before, Suspecting Temperature sensor and ECU goes way too far.
I had the exact same symptoms on my 2004 W209 with M112 (240) . All light come on when turning the key (except Water Temperature which remains 0 or blank) and few seconds later the Radiator Fan goes on full speed.
It turned out to be from the start enable relay (I read here that someone called it K40). It is one of the black relays on the front SAM. Marked with Red Cross in my photo.
I opened the casing of the relay and pushed it by hand and Voila everything worked.
Just to make sure I swapped the two black relays and the symptoms changed. So, that was our bad guy.
Hope it helps.
Let's not call that a fix but a workaround: you bypassed the security logic at the relay.
It is a good old known trick.
DANKE
I didn’t bypass anything mate.
That was just the way I diagnosed the faulty relay.
Obviously I replaced the faulty relay and it is all properly working now. Cheers and happy new year.
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