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DSM CAS + MS - Loss of RPM signal when hot


Jan 11, 2010
I'm losing all RPM signal to my MS but only when at operating temp for 10-15 min. Let the car cool for 15-30 min and its back.

I suspect CAS is getting flakey when warm, just curious if anyone has experienced this?
I did work on a car where the CAS was working and then flaked out a few weeks later. It was a junkyard CAS, with the cover painted a dirty gold/bronze. A replacement CAS fixed the issue.

Before replacement, do you have any high-speed logs of it cranking when bad? Do you have any noise filtering enabled (you shouldn't)? When it dies, does anything else in a normal MS log go bad, like Vbatt +12v or TPS?
The reason that CASs fail is heat exposure as they are installed near the exhaust manifold in their original application.
Older CAS for sure, you do bring up a good point about the original application. The wiring is not bad but could be better.

Seems I did not save a high-speed log but looking at the MS log when it quit running, nothing else looks abnormal to me (12v+ and TPS happy). I did notice a sync loss error code 17 right before the RPM fell off the cliff. I will try to reproduce it one more time and get a high-speed log. Tt seems these CAS are not as cheap as they use to be, what's the preferred option for a new OEM quality replacement? Did the hyundai parts prove to be usable?
You could run a stock crank sensor so long as your signal conditioning circuit is better than MS's. Some people modify the intermediate shaft to get a cam signal using a Hall effect sensor. You could also use an EZK117 distributor to provide a cam position signal.