Slight shocking effect from ECU?

[madmike]

I have a '68 Charger, 440-4 bbl, 4 speed that I've re-assembled.  I was experiencing ignition problems, the car acted like someone was turning off the key momentarily, and then back on.  Sometimes it would just stall at a light for no good reason.  While searching for loose or damaged wires, I felt my MoPar orange box ECU, to see if it was warm or hot to the touch (while the car was running).  The orange box felt normal, but I did feel a numbing/shocking/electrocution sensation when I touched the round transistor on the back of it.  Is this normal?  My ECU was mounted just behind the carburetor, with an aluminum bracket bolted to the intake valley pan.  It might not have been sufficiently grounded, and maybe that's why I got shocked?

I replaced the ECU with a new one from Summit Racing (still an orange MoPar box), because I could find no bad connections or wire damage.  The car seems to run fine now, with no hesitation, stalling, or ignition cutting out.  However, even the new one will shock me, if I touch the back of the transistor, just like the old one.  I re-mounted my new ECU just behind the grill of the car, and I made sure it was grounded well using star lock washers.  I even ran a ground wire from the box directly to the negative battery terminal.

So, is it normal that touching this transistor will shock you?  It doesn't hurt, but I can definitely feel it!  I'm concerned that this module won't last long either, especially if it's doing that.  From Nacho R/T's posts, it sounds like the transistors are known to be faulty...

Thanks for any advice!

[JB400]

http://www.dodgecharger.com/forum/index.php?topic=100889.0

[Nacho-RT74]

I felt my MoPar orange box ECU, to see if it was warm or hot to the touch (while the car was running).  The orange box felt normal, but I did feel a numbing/shocking/electrocution sensation when I touched the round transistor on the back of it.  Is this normal?

on my 74 FSM catalog says when proceeding with ECU test with the propper testing tool that is posible to happen, so keep away from touch the transistor

take on mind on regular transistors with 3 leads consit on Collector, Base, and Emisor ( or something like that )... on these power transistors they have two leads, and the 3rd lead is the chassis

[madmike]

Thanks, fellers!  Appreciate the responses!  At least thee ole girl is up and running now, and the shocking effect is normal.  I guess I'll have to carry a spare ECU...

I'd rather change to a better ignition system, if these are known to be crappy quality and unreliable.

[Pete in NH]

HI,

I'm not sure what the story really is with these ECU's. They do seem to have gained a rather bad reputation as to reliability. I have an orange box on my 71 and so far so good. But, I think I am going to get a spare to carry. One issue I think may be effecting the reliability is poor grounding of the box. Mounting them on a fender well or some such place with self tapping screws likely does not provide the best grounding. I mounted mine with 1/4-20 bolts with external tooth lock washers and ran a separate ground wire from one of the mounting bolts directly to the engine block. The ground wire has ring terminals at each end and external tooth lock washers to bite into the metal. I also scraped off some of the orange paint on the ECU around the ground wire mounting bolt. Like i said so far so good, but time will tell.

[PlainfieldCharger]

Put a solid ground on mine too...no problems yet....but i am only driving mine around the block at this point. This was a problem for me on my 69 charger back in 84. Fixed it right up..