'75 CJ: electronic control module

The electronic control modual on my 75 CJ (304) got fried. Obvious black area on the underside. Started out as an intermitent problem (hesitation, stalling) and then became a permenant problem R)

So I swapped it out and everything works fine now.

Q: What's the likely cause? I'm wondering it I should expect it to happen again.

In other words, is this something that just 'happens' occasionally? Or do I need to hunt down a 'real cause.'

 

Seems to be pretty common. I'm gonna say its a combination of age aggravated by heat. The eary boxes (which you have) were not noted for being relilable from the get go. In 75 they were just beginning to figure this whole "electronic ignition" thing out. I don't think there is much you can do to solve things, other than switch to an HEI ignition, which eliminates the control box. Probably the #1 upgrade for an older jeep, for many reasons. I'm sure others will chime in with more detailed responses...

 

Oh yeah, the control modual that went bad was not factory original. It looked like an aftermarket replacement itself.

And fwiw, all my wiring is 'monkey stock' (stock, but has lots of crap dumb crap done to it over the years). Not in good shape but most stuff works.

 

The Prestolite ignition stock on a '75 isn't known for reliability. However, I've been running my '77 (last year for Prestolite) with a Napa replacement module for 3 years now, with no failures.

If you want to upgrade, see this thread http://www.earlycj5.com/forums/showthread.php?p=509993#post509993 for some options. Either the Ford Duraspark (used on '78 on AMC/Jeep) or GM HEI would be a more reliable choice than the Prestolite stuff. The biggest advantage of the HEI is the price of the parts, and that the parts are available everywhere. Either the HEI or the Duraspark with TFI parts would be a big upgrade in performance, aside from the reliability issues.

hth!