HiTech Posted March 1, 2011 Author Report Share Posted March 1, 2011 Googled 96 Yukon crank sensor: Answer Intermittent faults are very difficult to find. Is the vehicle displaying a check engine light on the dash and if so, You need to find out what CODE is being stored in the computer via a scanner. It COULD BE a lot of things and GUESSING can be very very costly. The most common faults are caused by moisture getting into the CRANKSHAFT SENSOR wiring connector or into the ignition module connections or various other electrical connectors. When the fault occurs you need to determine if you have a loss of FUEL, IGNITION to the spark plugs or ignition to the injectors before any diagnostics can be performed. yep read that too...i checked and clean the connector all of em ..339 if i remember right was the code ..its been a few days sense i checked that ..339 was crank sensor fault....that is where i started after it died ....102 was another one ..i think it said lean or vacume leak ..nothing that would keep it from running ...the one thing i havent done is quess..by spending money other that changeing the crank sensor .i am not the tpy who just throws money at one ..ill try everything i can to find the problem some other way ....maynot always find the asnwer .but i try ...thanks your help is not in vain ..i look into every thing you mention ...this has backed me back up to the crank sensor ...i dont know if i am not getting a ground through the crank so the reluctorcan do its job ..or if the reluctor has a problem .or has to much clearance.... Link to comment Share on other sites More sharing options...
KISS_Racing Posted March 2, 2011 Report Share Posted March 2, 2011 Fuel pressure seems to be critical on these. Also mentions watching fuel pressure gauge for leak down. Read where it say 58 - 65 psi. 55 psi is to low. Also, found where it says there is a vacuum on the return which many people have found to cause an issue. Link to comment Share on other sites More sharing options...
4cylfordz Posted March 3, 2011 Report Share Posted March 3, 2011 just a thought but have checked to see if the key that drives the reluctor wheel hasnt slipped, ( it is a shared key from the timing chain, and the reluctor rides on the very tip of that key.) also I wouldn't be too worried about an engine ground causing problems with the crank trigger because the timing cover is plastic therfore the sensor has a self supplied ground in it's harness, I would trace that lead and verify its transmitted signal location because it sounds like it just has a weak signal due to either a weak supply power(verify with volt meter). or measure the resistance between the pulse( triggered output) and it's destination... look at a diagram. Link to comment Share on other sites More sharing options...
HiTech Posted March 3, 2011 Author Report Share Posted March 3, 2011 just a thought but have checked to see if the key that drives the reluctor wheel hasnt slipped, ( it is a shared key from the timing chain, and the reluctor rides on the very tip of that key.) also I wouldn't be too worried about an engine ground causing problems with the crank trigger because the timing cover is plastic therfore the sensor has a self supplied ground in it's harness, I would trace that lead and verify its transmitted signal location because it sounds like it just has a weak signal due to either a weak supply power(verify with volt meter). or measure the resistance between the pulse( triggered output) and it's destination... look at a diagram.s i checked the reluctor .it is solid from what little i can get ahold of through the sensor hole .....cant get it to move.. not saying thats the best way to check it .. .and yes after further review .it is plastic ....dirty and didnt notice it was plastic at first .must be getting blind ...lol...ill pick up a better book with more infow ..just have alittle print out from work ..hard to follow it .i did notice the threaded incert on the hold down bolt for the crank sensor was pulled out of the cover some or looked to be ...dont know if its made that way .. so i dont know if that is has anything to do with it . ill have to check if the sensor is plum.....havent had the time the last couple of days to do anything with it ..........i said earlier aboult a ground problem manily cuz .if i try and start it ...my voltage drops too much ....from 12.5 to as low as 10.68...the battery is in great shape ..i load tested three times and it held up ..............does not always mean its good enough ....had a new batter in a racar back in the 80.s misfired alot at high rpms .after trying to find the problem most of the season ..changed batterys .and fixed it ....thanks dan... every little bit from yah helps ... Link to comment Share on other sites More sharing options...
MrX Posted March 3, 2011 Report Share Posted March 3, 2011 i did notice the threaded insert on the hold down bolt for the crank sensor was pulled out of the cover some or looked to be ...dont know if its made that way .. so i don't know if that is has anything to do with it. That is a big problem they had with the that motor the crank sensor is not aliened the air gap is off. Will cause a no start and it to run bad. there is service bulletin on this. Link to comment Share on other sites More sharing options...
KISS_Racing Posted March 3, 2011 Report Share Posted March 3, 2011 Look at this: Starting Issues Link to comment Share on other sites More sharing options...
HiTech Posted March 3, 2011 Author Report Share Posted March 3, 2011 i did notice the threaded insert on the hold down bolt for the crank sensor was pulled out of the cover some or looked to be ...dont know if its made that way .. so i don't know if that is has anything to do with it. That is a big problem they had with the that motor the crank sensor is not aliened the air gap is off. Will cause a no start and it to run bad. there is service bulletin on this. gm has a tsb on this ..ill look into it ..sometimes you cant find the dime your looking for when its in your left hand all that time ....so far everything i checked roled back to the crank sensor ...the code was crank sensor ..though i replaced it with two new ones .it hasnt worked ..seeing the incert and .being able to activate the fuel pump and ignition while running a wrench over it .has to be the problem right there ..gap ...im not very good at home computors ....do know where i can find that tsb .........other then going over to gmc ... Link to comment Share on other sites More sharing options...
MrX Posted March 3, 2011 Report Share Posted March 3, 2011 I can fax you one if you like Link to comment Share on other sites More sharing options...
HiTech Posted March 3, 2011 Author Report Share Posted March 3, 2011 I can fax you one if you like sorry my main computor is in repair..so at this moment cant fax .....i am useing the lap top at this time ...so if you will fax it to attention jesse..878-1467......thank you .. Link to comment Share on other sites More sharing options...
MrX Posted March 3, 2011 Report Share Posted March 3, 2011 I can fax you one if you like sorry my main computor is in repair..so at this moment cant fax .....i am useing the lap top at this time ...so if you will fax it to attention jesse..878-1467......thank you .. What is the area code. Link to comment Share on other sites More sharing options...
HiTech Posted March 3, 2011 Author Report Share Posted March 3, 2011 I can fax you one if you like sorry my main computor is in repair..so at this moment cant fax .....i am useing the lap top at this time ...so if you will fax it to attention jesse..878-1467......thank you .. What is the area code. sorry 361..cc tex Link to comment Share on other sites More sharing options...
MrX Posted March 3, 2011 Report Share Posted March 3, 2011 Fax sent. Link to comment Share on other sites More sharing options...
KISS_Racing Posted March 3, 2011 Report Share Posted March 3, 2011 HT, I believe that last link had TSB on it... Link to comment Share on other sites More sharing options...
doitinthedirt Posted March 8, 2011 Report Share Posted March 8, 2011 ok HiTech we have not heard anything since thursday, what has happened? Link to comment Share on other sites More sharing options...
lbeaver087 Posted March 8, 2011 Report Share Posted March 8, 2011 if the truck has a coil i would check it i have a much older chevy i changed alot of stuff an spent money after all i did it was a coil . on these chevys there is a main ground that is right at the thrumastat housing mine broke an the truck run like shit you would touch it it would run good take off it would quit Link to comment Share on other sites More sharing options...
HiTech Posted March 9, 2011 Author Report Share Posted March 9, 2011 .OOPS Link to comment Share on other sites More sharing options...
HiTech Posted March 9, 2011 Author Report Share Posted March 9, 2011 computor was down yesterday ..........WELL I HAVENT FOUND THE PROBLEM YET .I WORKED ON IT FOR A FEW HOURS SUNDAY ...THIS IS REALLY STARTING TOGET UNDER MY SKIN . .... THIS IS WHAT IT WILL DO .....I CAN TAKE WRENCH OR SWIPE THE CRANKSENSOR NEAR THE BLOCK WITH IT PLUGGED IN AND KEY ON ..IT WILL FIRE .I GOT IT TO START BUY SWIPEING AWAY WHILE TURNING THE MOTOR OVER ..RAN LIKE CRAP OFCOURSE . I COULD NOT KEEP IN TIME ..LOL BUT IT DID START ..SO I HAVE CHECKED THE RELUCTOR ..IT IS IN PLACE AND IN TIME ..I HAVE RAN ALL OMS AND VOLT TEST TILL I TURNED BLUE ...THE PROBLEM I FOUND IS WHEN I TRY AND START IT .I LOSE VOLTAGE .. BELLOW 11.4 AT TIMES ..ACTS LIKE A BAD CROUND ..BUT WHERE I HAVENT FOUND IT JUST YET ..THIS IS SOMETHING THAT NO ONE I KNOW HAS EVER SEEN ..AND I KNOW ALOT OF POEPLE WHO WORK DAY TO DAY ON CARS ....WHY IT WILL FIRE ONE WAY .BUT NOT WITH SENSOR IN PLACE ....THATS THE MILLION DALLOR QUESTION ..AND WE ALL KNOW IT IS PROBABLY A 5 DALLOR ANSWER THAT WILL FIX IT ...I AM GOING TO TRY A NEW IGNITION SWITCH ..ITS GETTING TO THE POINT ,I JUST HAVE TO SPEND MONEY AND TRY THINGS ..CUZ WHAT I HAVE DONE HAS NOT HELPED ...GOING ON THREE WEEKS WITH THIS MONSTER .... Link to comment Share on other sites More sharing options...
ratdaddy Posted March 9, 2011 Report Share Posted March 9, 2011 YOU REALLY NEED TO HOOK UP A SCANNER AND LOOK AT DATA WHEN CRANKING, I HAD A CHEVY IN HERE ABOUT 2 MONTHS AGO AND THE CRANK SENSOR WENT BAD, GOT ONE FROM CARQUEST, WOULDNT RUN, GOT ONE FROM O'REILLYS WOULDN'T RUN X2 FINALLY GOT ONE FROM GM NO PROBLEM. I DON'T KNOW WHAT THE DIFFERENCE WAS THEY ALL LOOKED THE SAME. AND MAKE SURE THAT THE CONNECTOR AT THE SENSOR IS NOT JACKED UP TO WHEN YOU INSTALL THE SENSOR IT POSITIONS TO WIRES TO LOOSE CONNECTION. AND WHEN YOU PULL IT OUT AND DO YOUR MAJIC WRENCH THING IT MAKES CONNECTION. I HAVE SEEN THIS ALOT WITH SPEED SENSORS. Link to comment Share on other sites More sharing options...
KISS_Racing Posted March 9, 2011 Report Share Posted March 9, 2011 HT, I have to agree with ratdaddy... I don't know if you know someone with a Tech II but you got something funny going on. Before you spend to much more time and money it might be worth it. Mark Link to comment Share on other sites More sharing options...
HiTech Posted March 9, 2011 Author Report Share Posted March 9, 2011 .i could have spent all night typing what i have checked and done with this truck .but the fact is .i havent got this problem solved ................checked the connector checked the wires .the pins .....even wiggled it while trying to start it and then some i to have seen bad connectors ..hell dodge was the worst with that problem .thats why i went there first .......i am going to revisit the crank sensor area .. ... i found a doner truck last night .i am going to change that connector ..and try the factory cranksensor ..i know this system works on this truck ...and kiss i know something is funny .and i aint laughing lol ...rat the sensor do look the same ..i have put em side by side and everything looks the same ..but i agree and thought aboult the after market ........the factory sensor that came out ..responds the same as the other two i tried ..that can throw you off when your finaly had enough ..at this time ill try just aboult anything ..even lighting this thing on fire if that would help ...i dont like buying parts for the sake of it ..thats probably one reason it isnt running yet ...like i said earlier ..a million dallor question .i hope yah had the 5 dallor answer ...i dont have a problem buying lunch ......and not at some cheese burger store ...ill spend more than 5 dallors ..this has to be something symple ..other wise it would be running ... Link to comment Share on other sites More sharing options...
neon14 Posted March 9, 2011 Report Share Posted March 9, 2011 This is how I check crank and cam sensors. First I bypass the auto shutdown relay with a jumper wire. With the ignition key in the on position. Unplug the sensor. Use a multimeter to check the wires coming from the computer. You should have a ground wire, a 12 or 9volt wire, and a 5volt wire. If you are missing any of these the computer is not on or there is a wiring problem. Now plug the sensor back in and tap into the 5volt wire with a t tap or something so you can measure the voltage on the wire. Now spin the motor over slowly by hand. If the sensor is working it will go from 5volts to 0volts (or very close to 0) back and forth as you spin the motor over. Remember, a crank sensor does not put a signal into the computer. It just pulls down the 5volt line. The other day you said you were able to get the motor to briefly fire by waving a wrench over the top of the sensor. It got me to thinking. This test will verify if your sensor is working correctly. Link to comment Share on other sites More sharing options...
KISS_Racing Posted March 9, 2011 Report Share Posted March 9, 2011 Ok wait! I found this as part of a troubleshooting and I have never heard of this before? "6 Connect a GM scan tool to the vehicle's diagnostic port and run the crankshaft position sensor variation learn procedure." Link to comment Share on other sites More sharing options...
KISS_Racing Posted March 9, 2011 Report Share Posted March 9, 2011 Usually no starts are a sign of faulty crank sensor or Engine coolant temp sensor (Sorry, from another forum) Tahoe Forum This guy is good. May be worth joining and PMing him.... Link to comment Share on other sites More sharing options...
HiTech Posted March 10, 2011 Author Report Share Posted March 10, 2011 i am going to burn this thing .....WELL I CHANGED THE PLUG AND CRANK SENSOR ..HIT THE STARTER AND WALLA .IT TRIED TO START ...THATS A FIRST IN ALONG TIME .BUT THATS ALL IT DID ..CHECK FOR SPARK AT THE SPARK PLUG AND IT IS DARK YELLOW ;BUT WILL SPARK OFF A SCREWDRIVER 3/8 OFF THE BLOCK ..THATS A START ..CRY OUT LOUD ....AFTER CHECKING A COUPLE OF MORE THINGS ..THE SPARK WAS STILL YELLOW .BUT NOW IS SPORATIC............ Link to comment Share on other sites More sharing options...
MrX Posted March 10, 2011 Report Share Posted March 10, 2011 One thing you can try that we have hit on is plug converters. pull O2 front off and see if it will start. Link to comment Share on other sites More sharing options...
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