Bad ESC Module?

[ninety6]

I'm working on my 86 C10 305, and it has ESC.

Hadn't run in at least 3 years, just sat on my uncles farm in a field...

I brought it home, and here's where i'm at:

With ESC hooked up, it cranks and cranks, but no spark (visual spark test while grounding plug) no start, etc.

I bypassed the ESC module by jumper green to black on the ESC connector, and it started up IMMEDIATELY on the first crank. It runs a little rough at low RPM, it cut out a couple times, but i was able to drive it up and down the driveway and keep it running.

Is it a fair assumption that the ESC Module needs replace? I don't intend to bypass permanently.

Also, i'm running 3 year old gas (gotta do something about that), so i'm sure that doesn't help.

I just wanted to know if a bad ESC module can cause no spark, and its safe to assume that a need a new one? Or, could the knock sensor or whatever cause that with a GOOD ESC module?

THanks for the tips. I was SO excited to get her running! I need to hurry up and start my projecte thread to track my progress!

[Axle]

Skip esc. Procure a standard HEI distributor to replace the ESC distributor. The only wire you need to reuse is the power wire, and you'll find a connector a few inches away from the esc distributor bat connector (inline, just follow the wire back until you find it, disconnect and connect to the regular hei bat terminal). Done. Well, almost done, still got to set timing.

Alex.

[BamaDave]

Interested....any pics of said connector. I just cut the entire harness at the firewall and pulled it all out.

[Hiluxxulih]

On my 1985 I had a bad wire that literally only had a strand wire left inside the wire coming off the little electronic unit under the cap .

[ninety6]

Originally Posted by BamaDave

Interested....any pics of said connector. I just cut the entire harness at the firewall and pulled it all out.

here's the connector and how to bypass... i just jumpered and didn't cut... i rarely bring myself to cut original wiring unless i really have to.

Overall, i'd like to get it working with OEM setup, using the ESC properly. Mostly just trying to confirm the behavior is indicative of a bad ESC.

[ninety6]

Received and tried my new ESC module today. Same behavior as old -- no start/no spark, but starts right up with ESC Bypassed. I did verify power to ESC and ground to ESC, so it's not that.

Took apart distributor, all the wiring and connectors look good. Picking up a new ignition module tomorrow, thats about the only other part of the ESC system....

Service manual states a bad knock sensor would just stop the truck from retarding the timing. so i don't think that would be a contributor to this, even if it was bad.

Will try again tomorrow night with the Ignition Module!

[BamaDave]

http://www.73-87.com/7387garage/drivetrain/escrepl.htm

[ninety6]

Thanks! I've read through that (and through that in the service manual it came from ;-). Hoping for the best tonight with the new module.

[ninety6]

Truck started up with new module and new ESC. So it appears both were actually bad.

I tested back and forth and it only started with new ignition module and new ESC.

However, after i finally had the new ESC mounted in it's proper location, the truck failed to start again. Bypass it -- fires up, plug in ESC, doesn't.

I messed around -- ended up getting it to be intermittent with the new ESC -- it almost seemed like maybe the ESC wasn't getting enough voltage during cranking to operate? (9.3 or something). but, connecting it directly to the battery gave me a little more during cranking and it started, then i disconneted the jumper to the battery and it ran normally.

Tried a few more starts, including letting it run for a minute in bypass, then turning off, plugging in ESC and starting immediately. started fine.

Was able to make it "cut out" by wiggling the connector at the ESC. Everything looks good at a glance, but the fact that wiggling it made it stumble, then run, then cut off -- makes me thing wiring.

Any chance this is a fusible link issue?

so many variables!

I'm getting more tempted to just bypass ESC and adjust timing -- but i'm kinda stubborn in doing it OEM style.

[ninety6]

FYI update -- my "new" esc module was defective. Even "tapping" on the module would make the truck run or not run. I replaced with a new one and all seems well. So end result in my case, the ESC and ignition modules were bad, and new ones have the truck running!

Luckily my defective ESC actually worked at first when i hooked it up, or i'd be hunting down nothing for no telling how long. It worked on initial hookup (after i replaced the ignition module), but then quit after mounting it back under the dash. Took about a week of playing, etc to figure out the new ESC was actually bad.

Will do a couple more days of testing, then reassemble the dash with the new ESC in it. I will, however, always keep a jumper wire in my glovebox in case this ever fails on the road! Glad i know how to bypass!