2004 W203 C240 4Matic (AT) Won't Crank
11-10-2014, 03:28 PM
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2004 c240 4-matic; 2015 VW GTI SE
2004 W203 C240 4Matic (AT) Won't Crank
Hello again MBWorld gurus. I received great consult from Glyn Ruck and others on a blown engine a few years ago and I'm back with another mystery. I've spent several days searching forums here and elsewhere for possible solutions to a no-crank issue without any success. However I do see this symptom cropping up so perhaps I've missed the correct diagnosis.
Like several others posting this issue, my '04 C240 (80k miles) was running fine but, without warning, refused to crank after driving and parking on a dry, warm day. I had the car towed home and subsequent tries over the next week all failed. Both keys turn through the start position, and all lights and accessories work fine. There's no apparent current to the starter (no clicking, dimming of lights, or voltage drop) in the start position. New battery this year, reading 12.5V, charging system fine, no dash notifications, no OBD codes present. I've checked all the primary +/- battery connections I can get to (can't get an eyeball on the starter, but it's dry and clean in that area). This is a garaged southern U.S. car and there's no electrical corrosion anywhere. I've changed fuse 52 to 20A, checked 31 and 57, and verified the K relay is working. The front SAM is dry and clean.
The symptom mirrors that of a bad neutral safety switch, but obviously there's plenty of circuits in this car that could cause the same scenario. I'm able to move it out of park, but trying to start it in neutral or while floating through the gears did nothing. Online searches give me no info on the NSS location but I did verify the shift rod is connected tightly to the transmission shift lever. I don't have the factory manual, so tracing circuits for bypass is beyond me.
Any thoughts, folks? I'm concluding that I'll need to get it towed out to a shop for a Star diagnosis, but hate to raise the white flag on what could be a home-fixable issue.
Like several others posting this issue, my '04 C240 (80k miles) was running fine but, without warning, refused to crank after driving and parking on a dry, warm day. I had the car towed home and subsequent tries over the next week all failed. Both keys turn through the start position, and all lights and accessories work fine. There's no apparent current to the starter (no clicking, dimming of lights, or voltage drop) in the start position. New battery this year, reading 12.5V, charging system fine, no dash notifications, no OBD codes present. I've checked all the primary +/- battery connections I can get to (can't get an eyeball on the starter, but it's dry and clean in that area). This is a garaged southern U.S. car and there's no electrical corrosion anywhere. I've changed fuse 52 to 20A, checked 31 and 57, and verified the K relay is working. The front SAM is dry and clean.
The symptom mirrors that of a bad neutral safety switch, but obviously there's plenty of circuits in this car that could cause the same scenario. I'm able to move it out of park, but trying to start it in neutral or while floating through the gears did nothing. Online searches give me no info on the NSS location but I did verify the shift rod is connected tightly to the transmission shift lever. I don't have the factory manual, so tracing circuits for bypass is beyond me.
Any thoughts, folks? I'm concluding that I'll need to get it towed out to a shop for a Star diagnosis, but hate to raise the white flag on what could be a home-fixable issue.
11-10-2014, 03:35 PM
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Check Start relay in the S cavity in the front SAM. Try taking power direct to the starter motor to ensure it's operational.
Make sure that Temp sensor & CPS conections are good.
Make sure that Temp sensor & CPS conections are good.
11-10-2014, 03:51 PM
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2004 c240 4-matic; 2015 VW GTI SE
Thanks for the prompt reply, Glyn. I meant to say that I verified the S relay, not the K. Re the starter, I only have jack stands in the garage and I simply cannot get to the starter (without dropping the exhaust system). I've got the 4-matic, so it's super tight right there. Is there any workaround?
I'll look up the temp sensor and CPS locations here on the forums (no service manual), but if you have any reference for me, I'd sure appreciate it.
I'll look up the temp sensor and CPS locations here on the forums (no service manual), but if you have any reference for me, I'd sure appreciate it.
11-13-2014, 01:12 PM
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2004 c240 4-matic; 2015 VW GTI SE
OK, no luck with the sensor connections being the issue. Any other ideas out there? Is there any incidence of a neutral safety switch or other similar starter interlock on this car?
