Replacement ECM

[MicrowavedBread]

I traced an issue back to the ECM and bought a used working one. When i installed it, it doesn't turn over.
I'm assuming there's a button/switch combination i have to do for the new one to start working in the truck.
Any help would be appreciated!

1994 Mighty Max 4G64 engine.

[camoit]

Have you checked to make sure the capacitors are not leaking. 90% that’s the problem.
Their is no switch to deal with.

[geezer101]

Hi and welcome to mightyram. Make sure the ECM isn't out of a 1990 model Mighty Max. This one model had a different ECM and engine peripherals - got a feeling this ECM doesn't get on well with other year model trucks. Also do basic checks to make sure it isn't another undiagnosed fault or you'll be chasing yourself and throwing money at it.

[B-Line]

ECM should be plug in and...play. If its bad or the wrong one then it will be immediately apparent.

[claych]

Welcome !
??? could you clarify the original 'issue' ??? which led you to believe an ecm was needed ???

[MicrowavedBread]

Cylinder 1 is was getting spark, but 0 injector pulse while all 3 others were running flawlessly. I checked voltage and continuity looking for shorts and there was nothing. When i unplugged the ECM and put 12 volts to the injector it triggered fine. In my head, the only thing that could be wrong is the ECM since cylinder 2, 3, and 4 ran perfectly. If you know of something i don't, please tell me

[camoit]

Is the engine light on?

[geezer101]

See if you can pull codes from it. It could be an input signal fault to the ECM as it's only affecting #1. Tough one...

[MicrowavedBread]

The engine light is not on. But it does come on at start up, so the bulb is good.

[MicrowavedBread]

It's not obd2 unfortunately, i don't have a way to pull codes that i know of

[geezer101]

Set it into diagnostic mode and observe the check engine warning light flash sequence. Labourious and old school, but that's how it gets done. OBD-I has mostly generic error codes that work across different vehicle platforms.

[claych]

Code retrieval procedures are in the WIKI section on the home page,(just above the classified section)
Under ECU & COMPONENTS .

You can make your own 'tester' for $3.00 tops.

--Also , remember an injector has 2 parts- electrical and mechanical... a broken pintle internal connection
will not prevent solenoid function (hence you will still get a 'click') However no fuel flow will take place !

[dash]

if u have an extra injector pigtail, u can 'pulse' the No. 1 injector while the motor is running
If the idle smooths out, the injector is good

Use a small screwdriver to scrape off the contacts (and bend em to increase tension) in the No.1 injector connector.

[claych]

dash ,
interesting, please do upload some pictures of Your above mentioned diagnostic procedure !!
Very Humble Thanks
P.s,
O/P may I impose for an update ???

[MicrowavedBread]

Sorry, haven't been able to look at it for a few days. I'll update as soon as i do though!

[dash]

It's a 'diagnostic procedure' .....and you need pictures.... of a spare pigtail connected to an injector ?
Well, here's another 'step' to the 'procedure':
I rap on the injector body with a 3/8 inch extension, simultaneously 'pulsing' and that usually "unsticks" them.
Very rarely not. Been doing this for years. Just revived my 1987 corolla GTS a few months back
Got it started, barely running, rough and shaking.
After the injector 'procedure', it now purrrrsssss like a kitten. Same 4AGE factory original 1987 imjectors

[claych]

It's a 'diagnostic procedure' .....and you need pictures.... of a spare pigtail connected to an injector ?
Well, here's another 'step' to the 'procedure':
I rap on the injector body with a 3/8 inch extension, simultaneously 'pulsing' and that usually "unsticks" them.
Very rarely not. Been doing this for years. Just revived my 1987 corolla GTS a few months back
Got it started, barely running, rough and shaking.
After the injector 'procedure', it now purrrrsssss like a kitten. Same 4AGE factory original 1987 imjectors

Interesting...
The picture request was not for Me, rather for the O/P's benefit.

[MicrowavedBread]

UPDATE: It had an injector code because i had the injector unplugged to check voltages. The injector plug has a constant 2-3v on it and never pulses up to 12v.

After pulling the negative cable and clearing the codes, its now just showing normal state. Resistance in the injector is at 14.5 ohms (perfect).


Have you checked to make sure the capacitors are not leaking. 90% that’s the problem.
Their is no switch to deal with.

I would like to know more about this capacitor, is it a separate capacitor for each injector? If so do you have any pictures?

[MicrowavedBread]

UPDATE: I i measured resistance of the injector and its perfect. I checked voltage on the injector side of the harness and its constant 2-3v, never pulses to 12.
I also checked codes and it had 0 codes. (constant short pulses indicating normal state)


Have you checked to make sure the capacitors are not leaking. 90% that’s the problem.
Their is no switch to deal with.

I'd like to know more about this capacitor. do you have a picture of which one and how to test it?

[geezer101]

The capacitors in question are inside of the ECM. I found a post of a stock ECM vs a badly botched repair on a similar ECM. The capacitors are the black components with exposed silver tops on them. When they fail they will bulge out and/or leak onto the circuit board and discolour it -

http://www.mightyram50.net/vbulletin/showthread.php/7627-Error-Codes?p=67420&viewfull=1#post67420

[B-Line]

Pop your ECU open and have a detailed look inside. Look for any burnt sections, or any wet surfaces. Its not always apparent until you look real close.

[dash]

out of curiousity I open my D50 ecu 2.4L
Had crappy repair job using all colored replacement caps from who knows where
Really purrs like a kitten tho. Surprised - lol
Not worried as megasquirt will replace the ecu then engine gets boosted