ok, its a 94 TA. I think the optical sensor in the opti-crap is on its way out. It started last night about 5 minutes into my ride. As I came to a light and stopped it was idling erratically and the tach was reading crazy **** from 500-3000 rpm but it was really only revving up to maybe 2000 then dropping back down to like 600 and anywhere in between, sometimes almost stalling out. A week ago it stalled on me once and wouldnt restart but after sitting for 5 minutes started right up and never happened again. I went to the shop today and scanned it with it running and as was setting up the scanner the SES light came on so I plugged in and got a code 36 (high resolution signal fault or extra low res. signal). The cap and rotor are about 2-3 months old, but I was getting a little surging around cruising speed here and there also b4 this started happening. Also, my alternator stopped charging briefly last week and I knocked on the case where the regulator is and that "fixed" that for now. Someone here posted about the alternator diodes going bad and leaking AC current into signal wires causing the PCM to do crazy ****,.....anyone have any ideas other than the obvious replacing the opti because of a bad optical unit? Oh one other thing,.....after i was testing the wiring from the distrib. test connector to the distributor, i noticed nothing out of the ordinary so I plugged everything back in and drove home. It seemed ok until the car got warmed up again, then the erratic idle started to happen again. Im guessing the electrical part of the trigger inside the opti is going bad and heat never does electrical parts any good.

 

I'm the one that posted about the diodes going bad. I would say you are on the right track but I would do a few things before I jump in to replace the opti. First, if you know the alternator is bad, replace it and the belt and tensioner. Seen to many old tensioners kill many an alternator.

Check all the connections for the feedback signals from the opti. In particular, the 4 pin connector directly on the opti. Seen quite a few that are corroded but haven't figured out why yet.

Last, check all the battery connections and grounds to be sure they are shiney clean and tight. Don't forget the 2 most important grounds above the starter and next to the coil. If it still throws a 36 after all that, time for the elbow grease. Good luck to you.

Dave

 

I checked both connectors for the opti yesterday. The one on the opti itself, and the one on the manifold both look to be in great shape. Alldata told me to check the purple/white wire for 5 volts at both those connectors and if I had 5 volts there that it was the opti itself. I thought that sounded a little too easy myself, which is why i posted here to see if anyone else had experience with this dilema. Im looking into getting another alternator now, i have gone through 3 NAPA ones and 2 stockers, so now im wondering about what slopok said about the tensioner being bad and taking out the alternator for one, but that may have nothing to do with my code 36 problem. Any other suggestions b4 I head back to the shop?

 

Always change the tensioner with the alternator. The belt depends on the amount of time it was on. My buddy taught me that lesson. Went thru 3 alts until he finally changed the tenstioner and lasted years after that. We could only assume the bearing was going bad and causing a jerky motion to the belt. In turn causing loading and unloading to the input shaft mechanically and electrically to the circuitry.

Your mechanic is probably right from experience but remember the signal still has to get back to the PCM from the optical encoder. If that line has problems somewhere else, it could also give you problems. I personally like the Vantage from Snap-on (too poor to afford the Modis). For viewing the feedback signals at the PCM for just such a reason.