Malfunctioning ECM?

Kronustor · Sep 9, 2018

Hey guys I have a 95 Ranger that dislikes me.
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-index/coil-pack-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.

RonD · Sep 9, 2018

Welcome to TRS

Have you checked voltage on these parts?
All should have Battery Voltage Key on Engine off

Test battery voltage FIRST, 12.3 to 12.8v is acceptable
Then test red wire at the coil pack(s) should be exactly the same voltage

What engine do you have?

Depending on engine, MAF and CPS should also have the same battery voltage, and it all comes via PCM relay and PCM Fuse
So all the codes could be related to bad connection

Computer(PCM/ECM) has several codes it can choose from for each system, it has chosen "Circuit Malfunction" which is usually a wiring or Power issue

kimcrwbr1 · Sep 9, 2018

Allways address the lowest number first. Have you gone through the wiring completely? Cleal all electrical connectors with electrical cleaner and put back together with dielectric grease. Sand all grounds metal to metal. Look for burnt bare or broken wires especially around the exhaust manifolds. Erase the memory and reset the computer by disconnecting the battery for 20 minutes then do a complete warm up and pull the codes when the engine is hot. You can use electrical cleaner or maf cleaner to clean the maf if you used harsh chemicals just replace the maf if the code returns. Always erase the memory and reset the computer if you clean or replace a senser.

Kronustor · Sep 9, 2018

It has the 2.3l 4 banger. Battery is brand new.
I cleaned all connections with electrical cleaner but i didn't use dielectric grease when putting the connections back together.
I tested for power at the sensors with a test light but ill go back in with a volt-meter. I also sanded all the ground connections in the engine bay.
I only found a broken wire for the egr which did give me an intermittent code that went away after i fixed the connection.

I tried replacing the positive terminal but the cable that's on the truck has 2 cables wrapped in rubber at the starter solenoid.

Can a bad alternator cause problems? I have also noticed that it runs better when the battery charge gauge read in the middle and when it starts running bad the needle lowers.

RonD · Sep 9, 2018

Dielectric grease is used on connectors, not connections, what that means is that dielectric grease doesn't conduct electricity, so won't cause a short.
But since it doesn't conduct electricity you don't want it on the metal connections, just on the plastic connector, the grease prevent moisture from getting into the connector

Voltage gauge will go down if RPMs drop below 650, should be stable above that

New battery will show 12.8volts
3 years old, 12.5volts
5 years old 12.3volts, and time to shop for battery sale

With engine idling, just after startup, battery voltage should be above 14volts, 14.3-14.9volts is OK, never above 15volts
Above 14volts is "Recharge voltage", its to quickly recharge battery after draining it with starter motor

After 5 minutes or so of idling or driving, battery voltage should have dropped below 14volts, 13.5-13.8volts, this is "maintenance voltage", keeps battery charged without boiling it
If it stays above 14volts battery will get "cooked"

Test red center wire at both coil packs, key on engine off, should be exactly the same as battery voltage.

Also red wire on MAF sensor, should also have battery voltage

Cam sensor on the 2.3l uses AC volts, so just see if connection is OK

Kronustor · Sep 14, 2018

Finally found my volt-meter.
The battery is brand new with the truck off it reads, 12.45 volts. Once on and after idling it reads 13.8 volts.
The voltage at the coil packs reads the same as the battery, same for the MAF.
The other 2 wires on the primary coil do not have a switching signal but instead a constant voltage what can cause this?
If the truck had an ignition control module i would think that is the problem but it doesn't so what else can i test?

RonD · Sep 14, 2018

New battery should be 12.8v at least, maybe it needed to get recharged
13.8v is good for running engine after about 5 minutes or so

It has an ICM but it is inside the computer in 1995 and up Rangers

An ignition coil is just what its name implies, a Coil of wire.
So if one end has 12volts then the other end of that coil of wire will have 12volts.
I doubt a volt meter would tell you when it's Ground is being cut, which is what causes the spark to go out on the secondary coil, it happens at engine RPM rate with Waste spark.

So if engine is idling at 600rpms then each coil in the pack is being ungrounded 600 times per minute or 10 times a second, and volt meters just don't react that fast, an old analog meter might bounce.......maybe

Unplug both coil packs
You could try hooking volt meter to Battery positive and then to either of the outside wires on the coil pack's 3 wire plug, unplugged from the coil pack, and then crank the engine, at 200rpm you should see voltage pulse if ICM is working.
Test all 4 Grounds

Malfunctioning ECM?

Kronustor

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RonD

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kimcrwbr1

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Kronustor

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