Another electrical gremlin-help!

[kwimmer]

Been working on this all wkend but no joy. Symptoms: with engine cold, i get the WTS/WIF lights, they go off, i start truck and we are happy for about 2 mins. then i lose charging and overdrive. This is consistent. Afterwards, If i shut the engine off and go thru the restart process, i do NOT get the WTS or WIF lights but DO get antilock light but engine will start. Engine is warm enough not to switch on grid heaters with 1st start - block heater was plugged in. I have cleaned the grounds - block, fender, rad support, alternator, grid heater. i chkd for fault codes but all i get is "12" which no one seems to know and of course the "55". I built a bat tray to hold (2) Odessey 1700 bats and both are in good charge. i have NOT had the bats tested nor the alt. - they seem fine for the initial 2 mins as stated. I removed the CPS and cleaned it and reinstalled with no diff - again good for 1st 2 mins. im going to taint the idea process and say the it seems that once the engine temp reaches a certain point, something that should switch on/off backfires and the computer farts and i lose systems. Since this is my only mode of tranport i need accurate ideas to fix along with test procedures since i can't travel very far. Thx one and all!

 

[Greenleaf]

Pull the connector apart at the #1 valve cover. That is for the crank sensor. Be sure the connectors inside mate tight to one another. And, that they are clean.



You can also test the crankshaft pick-up for operation and adjust the gap. The manual will allow you to test the wires and the sensors. I don't know what the specs are on them off-hand.

 

[kwimmer]

added info

Well i tainted the ideas myself - its not temp related. this morning and managed to drive about 5 miles before it crapped out. engine was warm but not to its normal run temp. Fortunately, i was at my destination so i did my business and came back out and its started w/o problem - all bells/whistles functioning. Then i took the truck for its annual inspection and it crapped out again and would not reset. passed inspection though. :-laf i read the testing of the CPS for gas engines which just chks for resistance across 2 wires. Can this be done on our CPS and if so which 2 wires do i chk? I chkd RockAuto and a new CPS is $81. Again, THX.

 

[kwimmer]

i tested the resistance between the bk/lb post and the gy/bk post. these correspond to the testing posts for the gas CPS, i think. i registered 14K ohms. according to the manual, for gas CPS i should have gotten a "0" reading meaning no resistance. does this sound correct? i am going to test again when the system craps out to see if i get the same value. BTW, this morning, i went out to see if everything reset, i had not plugged in the block heater and it was under 60 degrees. i turned the key and all the bells/whistles were there. just for fun i disconnected the CPS and turned the key and again, all the bells/whistles were there. go figure. I wish there was a logic flowchart for the ECU. Thx.

 

[kwimmer]

Fixed, yeeeeHaaa

well boys & girls, it turned out to be the ECU, no wait ... the ECM, no that's not it - the PCM! No, its the SBEC. Got a rebuilt from RockAuto for $166 plus $100 core, plugged it in and wha - la, a functional truck. Kept the original CPS on the truck so that was not the prob. Should have read MBullwinkle's post from 2006 before i bothered with this thread. oh well. Thx.