cpnwrench

arrrrrgh!


Howdy, posted just a bit ago to older threads, but I haven't been here in a while.


I know the CPS takes an 11 mm wrench/socket. I know the code for 1991 is a "11" in the check engine blinky routine. I get a "12" ummm, my shop manual has NO info for a "12" code ( ECM stuff).


I just returned from Afghanistan, via NY 33 below in upstate, the trekking here to the SW. had to do maint on engine as Waterpump growlin bad. replaced with belt and tensioner and thermostat and hoses etc. she started up after all this, no leaks...this without air cleaner box on. I then shut off and installed air cleaner box and tried to crank and no go......first thing come to mind is ECM....but I see no shorts or frayed or crimped wiring etc etc etc. and symptom is reminicent of a previous CPS fail I had in the rain in Virginia......here is the question......according to the manual does the ohmmeter reading of "OPEN" as a GOOD sensor mean between A and B leads the BOTH WAYS should read OPEN..i.e. reverse POS and NEG leads when testing A and B reading.....??????


I am pretty much suspecting that it is indeed the CPS, it has been 100 thousand miles and like 6 years since I replaced it. anybody?


cheers!
cpnwrench

cruiser54

First off, welcome back and thanks for your service to our country.

Is it possible you bumped the CPS connector or something? I don't know the test for your Jeep's CPS but I know there is one out there.

cpnwrench

Hey Cruiser! Thanks for the reply,


naw, I did all that stuff... it is bolted well into the tranny case,. I did a precursory wiggle test and start test, more wiggle test, start test etc on the wiring.... am just curious as the 1991 code set says 11 is the CPS for sure....but....no indication of what a 12 code would be.....other than what is indicated for the 4 cyl and V6 models. which,.....has me scratchin and well the umentionables area! hhahahahhahahha! ANYWAY...... based on my history with ol red, she just decided to fail the CPS after I gave her a fresh water flow system!!!!!!! Man was that old pump bad!!! I could oscillate the whole rotating assembly like someone stirring cake mix in a bowl! funny that the bearing went before the seal indicating waterpump fail. hmm.
anyway I have a new CPS on order, should get tomorrow, from Oreilly, 64 bucks LIFETIME warranty! yeah I know dealer etc etc etc.. but I called them an they want 110 bucks!!!! I was like WHAT THE F&*&( ?????


anyway, was curious as to if anyone tested with a meter a GOOD sensor and what the ACTUAL meter readings were as I experienced a semi-short when changing leads (reversing) on the connector. see, according to manual it only says check resistance between A and B leads, it should read OPEN. It does not say reverse leads and see if it still reads OPEN. Hence my query....


Cheers sir!
cpnwrench

cruiser54

IIRC, 12 was the first code displayed at the start, and 55 was the one at the end?

cpnwrench

YASSIR! 27 lighters on my dresser, yessir.......


kiddin...alright, at first, I thought maybe, I saw a "11" blink code. but I then re-disconn battery and then rec0nnected and tried the 3 turn key to check the engine light blink sequence and yes... a 12 then the 55 (55 meaning end of sequence)......am still unsure, but same time kinda leaning to CPS....here is my thoughts, a defective O2 will cause crappy running, not necessarilly a NO-START condition right?
arrrrgh
?


all the best!
cpnwrench

cruiser54

Thanks for the memory jog. 12 is "battery has been disconnected".

cpnwrench

Cruiser54,


UNLESS..........this is far fetched....... ok, so I have water pump and thermo housing off to clean and ensure all mating surfaces are clean, etc etc etc etc,,,,now with hose running water and the drenching to clear out debris and such the natural gravity aspect of the small angle of driveway , blah, blah blah, the front end in a higher plane than rear end , bear with me, so as I am "purging" the block etc cooling area, the water flowing out is rivuleting down along the driver side of the block and one of the securement fasteners is the connector for the O2 sensor pigtail and wiring. Am thinking is it feasible that this purge of water may have saturated that connector system causing a dead short....Yet I find it not to be cuz it did start, just with no airbox, filter etc. Naw, I think it is CPS. but am writing her to make sure, cuz all you guys rock! with the knowledge!


arrrrgh!


all the best!
cpnwrench

belvedere

CPS is sure a good possibility. Have you checked for spark and fuel (to see which is missing)? Can you hear the fuel pump run?

cpnwrench

....Mr. belvedere....... rhymes with "lavender" not really, but hey.


anywhooooo......fuel pump primes right up, I hear it well and I smell fuel when crankin. I am just leaning that way towards CPS.. A coincedental event after replacing all the water pump related parts. your insight further bolsters my suspicion...am just curious as to anyone out ther VALIDATING the ohmmeter test on the CPS itself.


all the best!
Cpnwrench

cpnwrench

Ok, so I want to firstly thank all for reading and replying! For this particular issue. I do apologize if I may have come off the wrong way with anyone out there, this is a excellent place to discuss problems on our Jeeps, and to share experiences of troubleshooting!


MY CPS problem went away. This has got me befuddled. SO, I go to buy a new CPS, at Orielly, I then install the new one. and the jeep starts up but very rough, I mean very rough. so I then run the key sequence to see what codes are being put up and lo and behold I get a 27. this is odd I think. so I take off the "new" cPS and install the old one. it starts up but is running fast at idle, I see then that a vacuum line to charcoal canister is cracked, hmm, so I shut off and fix that, then try to re start, no go. am scratchin my head now I have to say. so, I then run another key sequence to check for codes. I now see a 22 (coolant temp sensor)...hmm I disconnect battery and wait like 30 seconds. I then disconnect the CPS AND the coolant temp sensor (on thermostat). I reconnect battery and reconnect CPS (still the old one now),,and re connect coolant temp sensor. I then try a restart and VROOOM! starts right up! but now I have the check engine light on......solid. I take a chance an shut off the jeep. a restart is good so I now know something threw the computer off in a wacky way. I then see that the code for the coolant temp sensor is still in memory. (22). So I go to O'reilly and buy a new one ($14) I install and viola! she runs like new. , I think now that when I changed out water pump, and stuff I never disconnected the battery, so maybe its possible the elec fan connect and the coolant temp sensor threw the ECU (computer) for a loop when I put everything back together. Just wanted to write and give everyone a heads up, that it is possible, that when a CPS fail symptom is evident that it may just be the CPU going a bit wacky.. Thanks so much again for the support!


Cheers!
CPNWrench

Radi

Nice work- glad it's running!

Roler

I've read a few times now, that bad coolant temps sensors can give these strange "CPS" like symptoms....

belvedere

Congrats on getting it running. If it were me, with intermittent electrical issues, I'd clean up all the ground points in the engine compartment (along with battery terminals).