Is it possible? Common? Likely? That my CPS is bad and fails only when hot? Ohms "open" like the new one sitting here cold? How likely?

I know it is common in an ignition coil but not sure about these?

As other threads state... new plugs, cap, button and coil already... Fail to restart after a 5-10 minute run time.

Brent

 

When things heat up they expand. Electrical components are no different. If the connection is broken but pulled together when cold one could surmise that heating and expanding would open it.

 

Seems with CPS issues, they generally just fail... But ya never know... If you haven't gotten it on a code reader yet then I'd say make that your next move. Even it the CEL isn't on, that doesn't mean there isn't a code stored in there.

 

He doesn't need a CEL. He has checked it with a DVOM and confirmed it is failed when hot.

OP - the only thing I would caution against with your test is that a lot of position type sensors swing from 0 to 5 volts. I would spin the engine and watch the DVOM to make sure it stays open as the magnets spin past it. It is possible that it is an on/off type sensor (all it needs to be really) and being open may be part of it's parameters.

 

key on off method check the codes

 

Sorry lemme clarify...
Sensor tested open (fine) cold as did the new one.
already removed to make sure new one was correct before leaving store. ohms not tested when truck was inoperative. It started fine after being dragged home.

My question was, is it likely or common for them to fail intermittently such as when hot.

I did run codes before removing CPS and got a 12, then code 11 then 55.

Brent

 

I have personally never heard of such a thing in dealing with a possible bad CPS. They usually just are good or bad. However, your CPS is basically a coil that picks up when the magnet on the flywheel passes by it. In theory, it could develope the same issue an ignition coil does where it is bad when hot but not when cold. If it works when cold but not when hot...and it reads good on your DMM when cold but not when hot. I'd say it is a good bet that if you dropped the cash for a new CPS that it would fix your problem.

 

Already dropped the cash, just hoped to hear it was a common symptom.

Couldn't test when symptom present...

Crossin' fingers and ridin' out and hopin' fer the best.

brent

 

Brent, nice to meet you. Let us all know if that fixes it.

 

Likely - heat-related failures are common in electrics and electronics, and they're intermittent at first.

This is why I have a common hair dryer in my toolbox. If I suspect a heat-related failure, I'll start with the engine bay DEAD COLD and specifically head up the suspect component. If the engine won't start or run properly, I'll replace the component I just heated up.

I've saved dozens of hours and a few thousand bones by having bought a new hair dryer every few years...

 

I would be more concerned about the code 55.

 

They mostly will fail when HOT (Intermittent) They will start to work again as the car cools down. On top of that when i took apart the connection their was all sorts of crud in there -so i used contact cleaner on the car wire side with a toothbrush and PLENTY of dielectric grease when putting the coupling back together.

 

Seems the CPS was bad. Many miles and several trips later and wifey is happy as a hog in slop...

Thanks for all the help with this issue.

Brent

 

Yeah, mine would only fail when hot to. Not totally fail (most the time) After hot restart it would idle rough and detonate bad till I got air flowing, replaced cps, all gone.

Not just a fluke, it would do it EVERY time in the summer when I would drive, park then drive again 5 min later.