Generation IV External Engine - Crank sensor problem
02-27-2012, 12:29 PM
I've been having a problem with my crank sensor on an 02 trans am ls1, at first I went to o'reilly's and I went through 3 of their sensors in a week, every time it'd do good for about a day and then it'd always go out on me when I was on the interstate, finally went and got the sensor from gm, that one lasted for almost a week and it just went out this morning on my way to work, is there anything else that could be wrong causing the crank sensor to short out or something? The plug and wires for it are still good, there's no fraud or bad spots in the wires
02-27-2012, 12:51 PM
what do the bad sensors look like when you pull them out? any corrosion or wear?
02-27-2012, 01:34 PM
No nothing, they look brand new, just a little oil or whatever on them
02-27-2012, 06:17 PM
02-28-2012, 06:02 AM
Installing a original equipment part was definetly the first thing to do. I worked at the dealership level for a long time and I can't believe there is anything that caused harm to the sensor outside of physical damage. The way the problems occur would be helpful. As in runs poor or just quits. I would want to pay close attention to the condition of the connecter terminals. They can get bent but might look ok at first. Then wiggle test and load test harness. If that all good tap test p.c.m. also are u using scanner to monitor rpm?
02-28-2012, 09:34 AM
Ok everytime it goes out I've been driving, 3 times on the interstate and the last time I just pulled out of a gas station, the car would just cut out a few times and my rpm gauge would start acting up, then the rpms would drop to zero and the car will shut off, sometimes it'll crank back up but it won't show any rpms on my cluster and and when you try to give it gas it spit and sputter and pop and then shut off
02-28-2012, 09:37 AM
Oh yeah and I was checking it with a snap on scanner and it's not reading any codes, after the 2nd time it went out I checked my plug and the wiring and it all looked good, no bent pins
02-28-2012, 10:19 AM
sounds like it could be a grounding issue... Double check all the wires and make sure you have a solid ground connection. We just had a car in that had the exact same problem, and there was a wire that had the insulation melted off and that was the problem.
02-28-2012, 12:37 PM
The ipc gets class 2 message from pcm for rpm. Tach will go to 0 if the pcm detects a malfunction in engine speed sensor circuit or ipc detects a loss of class 2 with pcm. So no engine code for crank sensor. Not unusual but may rule out first thing but how about making sure pcm is not droping out. Need to check for codes in other modules. Clear them after righting down and rechech what comes back. Getting long winded I know but lots of possibilitys.
02-28-2012, 12:48 PM
I'll check it out when I get off work this afternoon, I'll check all my ground wires too
02-29-2012, 10:08 PM
Ok finally got around to putting my car on the lift but it cranked up and after a minute or so my rpm's jumped up and started working again! So what the hell, gotta be a loose wire somewhere right?
03-01-2012, 05:41 AM
Ok you said the engine fired up right away I assume. That tells me crank sensor reading. Tach inop. The Tach gets class 2 from ecm. Get out scanner and monitor/ read codes etc. In all modules.
03-01-2012, 05:50 AM
I guess I should add that if other modules keep setting codes for lost comunication with pcm then you will have to look at power ground and data lines for pcm and then possibly faulty pcm.
03-01-2012, 07:43 AM
Yeah it fired right up and after it ran a minute the rpm gauge started working again, then I backed it out of the shop and as soon as I hit a little bump the rpm gauge dropped to zero and started spitting and sputtering and shut off again
03-01-2012, 11:19 AM
This tells me that you may have any of these:
- bad wiring between CKP sensor and PCM,
- bad PCM,
- crank thrust bearing has too much end play,
- CKP reluctor wheel is walking around on crank.
03-01-2012, 12:22 PM
Yea like joecar says possible reluctor issue but if you think a little bump did it then fire it up and start wiggling wires and tap on pcm see if you can duplicate. If reluctor moves away from sensor than sensor output drops and can act like running out of fuel.
03-01-2012, 12:55 PM
Ok I just thought of something, it all started when I got back from being out of town a month, the battery was dead and my buddy jumped the car off for me but he hooked the battery cables up wrong at first, think that could've blown something?
03-02-2012, 07:52 AM
I think I found the problem, where the wire for the crank sensor goes into the harness it looked like it had been touching my headers, the wires were brown burnt and cracking, so the wires were exposed. I taped them up best I could and routed them different so they wouldn't be touching the headers, now it's runs fine so I'm hoping that did it, but today I'm gonna see about getting some of that heat resistant hose to put around it
03-02-2012, 12:29 PM
Yea sounds like u found it. But those wires need to be sealed up better. I Like using uninsulated butt crimp connectors with self sealing heat shrink. U Want to get the insulation back together.
03-02-2012, 12:47 PM
I was gonna see if I could run all new wire down cause electrical tape and heat don't mix well haha, I just temporarily taped it so I could back it out of the shop, I gotta go get some of them crimp connectors after work