Ressetting a camshaft position sensor...

I blew a head gasket a couple of weeks ago and would up with water in the crankcase.. I didn't realize the gasket failed until 3 days later since there was no smoke out of the pipe and I falsely diagnosed a loose hose clamp as the reason I was losing coolant. It wasn't until I noticed the resevoir slowly draining as I watched it while the truck idled in the drivewaydid I realize that I was in trouble. Thanks to Mobile 1 synthetic(at least I'd like to think so) the cylider walls didn't score..Keep in mind I drive 85mi/day @ 60-80mph so I was pleasently amazed.
I had a par of remanufactured heads put on and all fluids put back in. I needed to circulate some oil for @ 500 miles then flush again for the syntec refill to make sure all of the water was out of the motor. I also needed to have the cam position sensor reset since there was a Service Engine Soon light on and I needed to have a clean engine before running her 137k mile engine up to 4000 rpm to set the sensor. Unfortunately the reset was done by my local shop through my diagnostic port.
As I drove the 1/4mi home the Service Engine light came on so back she went and a reset was attempted with no luck . It wouldn't hold the setting. The truck runs like she was new, but the light is on. My guy said that the Distributor may need to be replaced because the Mag. trigger may faulty.
I'd like to just try replacing the sensor itself for @ $30 before swapping the distributor. I can buy a new or re-man. distributor, but is the install just a 'loosen the retainer clip slide out the old -slide in the new and tighten up the clip again'? Or is it more involved?..Either way it appears that the Cam pos. Sensor needs to be set with a diagnostic connection..unless there's another way... All info is welcome.

IF it is a p1345 code get a scanner that reads live GM "CAM_RETARD" raise engine to 2000 rpm and move dizzy till you reach 0.00 degrees +-2.0 degrees. Zero is better lock it down and recheck with same method.

Guessing the 'dizzy' is the distributor..(haven't heard that one if it is). I was under the impression that unlike the older points distributors where you can advance and retard by rotating, the newer computer controlled engines self adjust regardless of position?... I unfortunately do not have a scanner and am reliant on the mechanic for that. I priced our a replacement at Summit and would swap it out myself if it's a driveway repair.. But if I can't clear the code without a scanner it's got to go back to the shop anyway. I'm guessing this isn't a disconnect the positive off the battery and wait 10 min kinda fix..

the alignment of camshaft and crank shaft sensor sensors must be pretty much dead on in sync. That is adjusted with moving the dizzy because the cam sensor is mounted to the distributor body while the rotor is always in a given position to the crankshaft. The computer will adjust timing of ignition system on its own but it does it by altering where in the engine rotation it decides to release the energy from coil. But it needs a fixed reference between the two sensors. if it is to far off the spark timing may be to far from from the point where spark can jump the gap between rotor and cap properly. Watch the following video to see the computer change timing by altering when it releases the spark energy. http://www.youtube.com/watch?v=f9tjjxyEnbY

Makes sense. thx for the link too..Seeing the gap jump is pretty neat..Pull another wire down the firing order and it's a poor man's displacement on demand..lol
Comet you truely are a wealth of information.

I wound up upgrading to a Summit aluminum distributor.. Waiting for my next oil change to get the cam position sensor set. You need a 'computer' to do it..no way around it.. I just don't like bringing the old girl up to 4000 rpm to do it- regardless of how smooth she's running..

VooDoo, you do not need to run the engine up to 4000 rpm. All you need to do is snap the throttle so the rpms go above 1000 and the cam retard reading on the scanner will reset. Adjust the distributor if needed and snap the throttle again to get the new reading. If "0" your good to go.

Firetow17 said:

VooDoo, you do not need to run the engine up to 4000 rpm. All you need to do is snap the throttle so the rpms go above 1000 and the cam retard reading on the scanner will reset. Adjust the distributor if needed and snap the throttle again to get the new reading. If "0" your good to go.

Click to expand...

Snapping the throttle does not "reset" the reading on the scanner. On the 1999 models the reading must me monitored while engine speed is maintained at 1000 and again at 2000 rpm.