I have several ECU boxes that I was testing on my car to make sure they work as I want to sell some of them. They all work properly except for one. It is a Mopar Performance chrome box and when I plug it in to my car the engine won't fire. Can ECUs be repaired? If it was a plain ECU I would just toss it but being it is a MP chrome box I'd like to repair it if that is even possible.

Yes, there are several companies that offer repair services for ECU, ECM, PCM or whatever name the use. Most of the major auto parts stores have someone they use or you can contact Cardone, Car Computer Exchange, in NC, SIA Electronics in Illinois, https://siaelec.com/ and probably a dozen others. Call your local auto parts store and ask who they might use? I know Cardone requires you to take it to an auto parts store as they have no way to do payments with a consumer.

Mike

Call some of them as they have a cutoff year for some models but they may be able to get you in the right direction for your ECU's,

Ecu isn't ecm isn't pcm. Nobody rebuilds ECU because they're so cheap to make new.

Ecm or pcm there us a market for repaired units.

i think the OP is referring to a "chrome box", not a late model computer control unit. [if i'm wrong, please correct me !]
if so, other than swapping out the round gizmo on the face, [i forget what it's called] they are not generally worth messing with.
by the time you remove the potting material on the back side, and screw around checking all the diodes, resistors, and solder joints, then fixing what you can, you might just as well buy a new unit if you can find one.
basically just not worth the time and effort to repair, just to try to get a few bucks out one.
just an old man's opinion. your mileage will vary.

They cant be repaired, but since it is a fancy MP part, rather than toss it away, maybe it could be used to convert into a stealth GM HEI module.

The one I replaced on my son's last truck would have been a great candidate for that. Completely melted potting, circuit board was dangling within. I'd never seen one that bare that hadn't been completely engulfed in flames at some point. But it actually ran good like that til it didn't... It was like someone flipped a switch.
To be honest though I have never owned any other brand of vehicles besides Mopar, I think that's one of about 1 that Ive ever had go bad on me... I've replaced them on fords and GMs over the years though

You are correct.

I did that with an old orange box I have , put an Accel HEI inside it .

I don't see anything special about a CHROME box since it wasn't a production line part used on a Hemi car .

There was somebody here doing it themselves. If I remember correctly what fails on these things is the transistor. If you have the number I'd be willing to bet you could find it on Digikey. Would never bother with any of the newer boxes - they're all crap.

I fixed mine replacing the transistor. Also a Mopar Chromed box. The harder part is get a GOOD quality transistor. Fortunatelly found couple of NOS Motorola pieces.

They don't really make the proper transistor anymore. If you can find on, it's usually made is some sub-third world sweat shop with all the QA that implies. A few years ago I found a suitable replacement transistor for this ECU's, but the Mouser cost was more than a new ECU, lol.

Yes, an Orange or Chrome box can be repaired, but it is not really cost effective if you don't DIY. I can do it, but I don't because that is real old tech stuff and I prefer to run a Microsquirt setup.

. [/quote]I did that with an old orange box I have , put an Accel HEI inside it . [/quote]

John - how does one go about putting an Accel HEI in an old orange box?
I'd be willing to do that.
Any chance to get a better ignition & get rid of the ballast resistor is a good thing.

I bought two of the Standard brand replacement ECU, a 4 wire and a 5 wire, from my local NAPA store. I wasn't sure which one was better so I will try both and see which one I like the best

The only difference is that the 5 pin is exactly the same as the 4 pin but with a dummy 5th pin so people wouldn't complain that it didn't have 5 pins like the original did.

Improved design did away with the basing resistor (the extra two prongs on a 4 prong ballast) that the 5th pin was used for.

transistor...........that is what i couldn't remember the name of. CRS disease ya know !
thank you and MarkZ for clearing my cobwebs a little bit.
gutting the chrome/orange box and using a gm HEI module is really pretty simple after you get the potting material out of the bad box.
diagrams and how to's are readily available, and would be the way to go instead of trying to find a quality TRANSISTOR [i remembered the name ] to repair the original box.

I melted out the goo they use to encase the electronics, hold it upside down and wave a torch under it, stay far enough away to not burn the paint. Once you get enough of it out the board is easy enough to remove. I made an alum plate to mount the HEI to, attached it with the screws that hold the the transistor on the outside , used longer screws that looked the same, heat sink compound between the HEI and the alum and wired the HEI to the orange box plug for power and the connections to the Dist. pickup.

This one might have the needed Motorola transistor.

https://www.ebay.com/itm/235109901514?

The chrome box uses the MJ10012 transistor

Be very, very careful when shopping for a replacement transistor...

The MJ10012 transistor is a generic NPN darlington available from multiple sources, since we deal directly with procurement from China sources we have found these costing from $1.25 up to $9....
Best to buy from an established USA source such as Mouser or DigiKey.

Just my $0.02...