88 GMC 1500 no start

[tayto]

i believe the CEL should come ON and then turn off after a few seconds but my memory is fuzzy and I don't have a TBI vehicle at this time to confirm. you can try reseating the PROM pins E & M are for data and different vehicles use different pin for data. i would test pickup coil see attached imagine. i have seen pickup coils test ok but fail when hot.

[tayto]

distributor can be tested in situ. im not a fan of dielectric grease as a heat sink compound, I use the stuff they use for CPUs on personal computers.

[Double Snowman GMC]

OK now, my no start is solved thanks to the Forum telling me where to focus! Woo Hoo!

I went back to check the Pickup coil and found the red connector to the ignition module loose (which I installed in some haste when I swapped back to the original 1988 ignition module)

So I guess I’m somewhat confident that this no start problem was the new/faulty ignition module I installed 6 months ago??

Buoyed with this success to get back drivable I plugged in the ALDL cable while the engine was idling ....and it immediately sped up 50 rpm.

Why does plugging in an open ended data cable shut down the truck one time and then increase the idle the next time??

I do see 4 rows of data in WinALDL, but it seems like I should be using Tunerpro??

Thanks for all the help so far,
Bob W

[tayto]

i assume the red connector is the pickup coil wires that plug into the 2 pins on the back of the ICM. I've had a moates OBD1 cable for close to a decade now and never had the issues you are having. does your cable have continuity between terminals A & B?

[Double Snowman GMC]

Ya, the pick up coil to ICM was loose on the swapped in ICM
No continuity between A & B terminals on the data cable.
Is Tuner Pro the best software for my application?
It seems like my truck is somewhat haunted.....with a mind of its own

[Double Snowman GMC]

PS. My IT guy (son) says we tried to download Tuner Pro off the internet, but our antivirus did not like it.

It also showed “missing DLL” errors.

[PlayingWithTBI]

No continuity between A & B terminals on the data cable.

Possibly it has a 10K Ohm jumper between A & B for older vehicles and TPI? My ALDL cable has all 3 options, open, jumped direct, and 10K Ohm resistor.

[tayto]

that's what I was thinking, maybe in field service mode. i remember messing around with an old handheld obd1 scanner and when you put it in field service mode the rpms went up. this was 15 years ago and I probably only played around with it for 30 minutes