Malfunctioning ECM?


Kronustor

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Sorry i think i posted on the wrong section, general discussion, and couldn't figure out how to move the thread or delete it.

It has been throwing codes:
P0102 Mass or Volume Air Flow Circuit Low Input
P0350 Ignition Coil Primary/Secondary Circuit Malfunction
P0351 Ignition Coil A Primary/Secondary Circuit Malfunction
P0352 Ignition Coil B Primary/Secondary Circuit Malfunction
P0340 Camshaft Position Sensor Circuit Malfunction

At first it was just the MAF and Camshaft codes, i fixed the MAF and before i fixed the Camshaft sensor the MAF code came back. After that Code 350 showed up and my primary ignition coil was not firing on cylinder 1, so replaced it and the code went away. Week later all these codes showed up.

I have noticed that the truck runs decent when i leave the battery unplugged. After 10-15 minutes the problems come back.

For the codes 350-352 i rechecked the primary coil and it no longer fires any cylinders. I plugged it into the secondary and it works fine. I checked the primary using this video:
https://www.youtube.com/watch?v=XcmWa2Bt12U
and this guide:
https://easyautodiagnostics.com/misc...testing-tips-3
and found it to be missing the switching signal.

any help would be much appreciated as i don't know if all the problems are related , failing ecm, or something else might be my problem.
 


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RonD

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Yes, could be ECM at this point, I would pull off it's 104 wire connector and make sure there is no corrosion inside.
You could test the 4 coil Ground wires at this connector, make sure the wires are good, they will be color matched.

If all checks out then replace ECU
California needed a Calif ECU usually, they had different emissions standards than other states
1995 was first year of the 104 wire ECUs in Rangers
You may be able to use 1995-1997 but not sure, 1998 got the 2.5l 4cyl engines

Same engine size ECU
ECUs come in Automatic Trans or Manual trans versions, that needs to match what you have.
2WD or 4x4 didn't matter
 
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Kronustor

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Thanks for all the help Ron.
I finally made a "breakthrough" on the truck the wiring harness has been messed and 4- 5 cables have been spliced im guessing those are the problem.
 

Kronustor

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where can i find a wiring diagram?

So i found this diagram and will try to use it to explain what i have found.
pin 100=light blue cable
pin101=white cable
pin 103,76,77,51,24= black with white stripe
pin 7= black with orange stripe.

so pins 103,76,77,51,24 seem to have been soldered together and they have shrink wrap on them. My guess is that these are probably ground cables

pin 100 and 101 seem to be twisted together and attached to a wire that is BARE

pin 7 is also twisted into a bare wire

I want to concentrate on pins 100, 101, and 7 for now as they are attached to bare wires.

Does anybody know where i can get a pin out similar to the one attached, it took me a good half an hour of googling to find this one.

I might try finding a new harness at the junkyard, this one seems to split into 2 the connection is attached to the air intake from there it goes to the fuse box and a couple other components.
 

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scotts90ranger

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That is pointing to a ground or power problem, and if the harness has been monkeyed with is definitely a good place to start... deal with those at work a lot, everything our engines go into has solid suspension (forklifts, cranes, zambonis, boats...) so things vibrate a lot and grounds break off, sometimes fuse pins corrode, or a connection is somehow overprobed or something... After checking on that yes the ECM could have a bad buss for the power or ground circuits, it happens but is less likely than you would think...
 


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