No spark-any professionals around?

[99DenaliMan]

I beleive it's a 91-93 sable (not sure if they are any different.) So, we where looking at the brain, because of a whacky problem I have never really seen before. It checked out ok. I decided to start checking the sensors. Well, checked the IAT, ECT, MAF, and fuel pump. Went on to check the TPS and forgot to put the Meter back onto Voltage from Amps. So, I put the power side in the back of the tps and the checked VD to ground. When I did this there was a spark by the TPS, and now there is no spark from the coil, which was not an issue prior. Never seen anything quite like this. I don't have a schumatic as to where the TPS wire runs to, but I'm guessing, PCM? There is a box on the driver side right underneath the hood, I'm thinking this may be the pcm, but it looks kind of small to fit a Prom, computer, etc. It has a letter J on it. The no-spark if the main the problem now. Prior to this the car would shudder very badly when cold if you floored the peddle, idled poorly, and drove just as badly. Also WHEN there was spark and the car would run. The RPM gauge would stay at 0 or near 0 when cranking, except when a jumper was hooked up, then it would jump to 7000 rpm bouncing off of redline while cranking, until the engine started, then the gauge would steady out. This would indicate a primary ignition system problem, wouldn't it? What strikes me as really odd, is that when hooked to a jumper it would bounce off rev while cranking. Even when the jumper wasn't hooked up the battery had 12.5 + volts and the engine would crank. The engine has been doing this for 3-4 months, just don't drive it very often. The no spark problem, well that just started after I tested TPS on amps instead of volts and I really need to fix that problem first. I pondered the question if the two where related, but if I let the engine crank 5-10 + seconds the rpm gauge will jump to about 4-5k RPMS now, and it has always had spark before this problem.

EDIT: 3.8 L automatic 145*** miles, and yes all fuses are good.

[shorod]

Two of the wires from the TPS do go straight to the PCM, the reference voltage (supplied by the PCM on the Brown/white wire) and the throttle position signal (supplied to the PCM on the Gray/white wire). The Gray/red wire is the signal return (ground).

I expect that your meter has a fuse for the current function. I would expect that fuse to be a fast blow fuse and should have blown before damage was done to the TPS circuit though.

The PCM should be mounted behind and above the glove box. You will need to disconnect the main harness from the firewall, then remove the mounting bracket and PCM from the glovebox opening after removing the glovebox door.

From you description of the way the tachometer had been acting and still is acting, I would suspect a bad ignition module. AutoZone might still be able to test them to give you an indication if it's bad or not.

-Rod