Did I damage my PCM?

[teeman914]

I replaced the O2 sensors in my truck a few weekends ago. My son had to help with the upstream sensor because of the plug location. He had to hold one of the plugs from above while I push the other end from under the truck. The female part of the plug (that my son had to hold from above) is suppose to be mounted probably somewhere on the firewall. This would allow one hand disconnect and reconnect. On mine they were just dangling. Oh well - we did got the job done.

Although during this project my son disconnected the wire harness from the PCM so he could reach down to hold that O2 sensor plug the was behind the engine block. And then reconnected it afterwards. We did not disconnect the battery for this.

The truck now indicated a P0352 - Ignition Coil B Primary/Secondary Circuit Malfunction.

Do you think we damaged the PCM?

Or just coincidently now have a coil pack problem?


Thanks,
Tom Koenig
Riverside, IL

 

[tbirdsps]

Probably not but you'd have to go throught the troubleshooting procedure for P0352 to find out. It's possible.

 

[LearjetMinako]

Unplug the battery. Turn the ignition on for a few seconds and the then turn it off. Reconnect the battery. Recheck for any trouble that may come back.

You may have just tripped a CEL. But clear the codes and see if it comes back.

 

[adsm08]

Its possible, but unlikely.

I would unhook the battery and then unplug the PCM again. Carefully inspect both harness and component sides of the connection for physical damage.

From there, get back to us and we will see if we can help further. If you didn't damage the pins I'll post up some diag info from Ford.

 

[teeman914]

P0352 trouble shoot

I was able to work a little on the truck today. I got a Haynes manual and checked out the wiring diagrams. They call the front coil (going by the wire colors) the secondary coil and the rear coil the primary coil. The P0352 code indicates a B coil malfunction. I am assuming the B coil is the secondary or front coil - please correct me if I'm wrong.

One of the procedures I read on one of the threads was to swap the coils to see if the bad one changes the code (I would assume it would change to the A coil). I did swap the coils after cleaning the areas they attached to the engine with some sand paper and cleaning the contact area of the coils on my wire wheel. Both surfaces were nice and shinny. I cleaned the plugs and where they plug into the coils with contact cleaner, also upon reassembly I use some dielectric grease inside the connections. BTW I broke one the specialty bolts (of course the last one I took out) that hold the coil to the engine obviously these coils had never been out. I was luckily able to get the stub out with a vice grips and lots of PB Blaster. Ford wants $9.00 each for the replacement - so be careful if anyone does this.

All to no avail the code still came back.

P0352 Ignition Coil B Malfunction.

The code appears about 10 seconds after I start it every time. I can turn it off with my scan tool and the code does not reappear as long as the engine keeps running. In fact if I drive long enough all the sensors go back to OK. I would assume I could pass an emissions test if I needed to as long as I kept the engine running.

Next I will try seeing if there is continuity between the location where the wiring harness plugs into pin 78 and 104 on the PCM and the tan/lt blu wire and tan/lt grn wire at the coil plug end - which energize the front coil (coil B if my assumption is correct).

There was no damage to either the harness or the pins on the PCM.

After that I will need some help. Can I test pin 78 and 104 on the PCM to see if they are energizing the coil properly? Or is it re-flash and/or new computer time?

The previous owner said he put new plugs and wires on the truck and they look it. He did use dielectric grease on the coil to plug wire connection and the plug wire to plug connection.

I did not take the plugs out. Maybe I should to see if there is a possible fouled plug?

Anyway I will try the continuity test and see if anyone can help thereafter.


Thanks for all the help so far,
Tom Koenig
Riverside, IL

 

[snake]

I am clueless on this one, but I agree I don't think you damaged a PCM by swapping O2's. If you think the PCM is roasted though, send it to www.ecmstogo.com - a place in Houston that can check it for u.

 

[teeman914]

After swapping the coils and still getting the P0352 coil B malfunction code I looked again at the Haynes manual for checking the coil packs. On page 5-4 it shows the testing procedure. 5.0 ohms resistance across the primary circuits and 13-15k ohms across the secondary circuits. I took both coil packs off the vehicle and tested the primary and secondary resistance. Both coils have open resistance on both primary circuits and both secondary circuits. Is it possible for the truck to run - which it does - with these two seemingly shorted out coils?

 

[Earl43P]

Type of meter? Range setting or auto-ranging digital?
Does it have a diode setting?
Did you try reversing the leads?

 

[adsm08]

Diagnostic Trouble Code (DTC) P0350 is an ignition coil primary circuit malfunction. DTCs P0351, P0352, P0353 and P0354 are ignition coil 1, 2, 3 and 4 primary circuit malfunctions.

Using a Neon Bulb Spark Tester (Special Service Tool D89P-6666-A) or Air Gap Spark Tester (D81P-6666-A), check for spark at all spark plug wires while cranking.
When using the spark plug firing indicator, place the grooved end as close as possible to the plug boot. Very weak or no flashing may be caused by a fouled plug.
Was spark consistent on all spark plug wires (one spark per crankshaft revolution?)


Yes
The ignition system is OK. REFER to Section 4A , Symptom Flowcharts.

No
Spark fault. GO to JE21 .

 

[teeman914]

I was in Walmart and saw a multimeter for $10 and thought maybe it is the meter that is not working. Sure enough. I tested the coils with the new meter and the primary curcuit tested at .9 ohms on both coils and the secondary circuits were 13.8k ohms on both coils. Just for grins I tried the test leads from the new meter on my old meter. You got it - my old meter showed the same results. So I'm just going to get a new set of test wires and keep my old (turns out to be trusty) multimeter. I'll give the other one to my son.

Getting back to the P0352 code.

I put both good coils back on the truck. Still the P0352 code.

Can I check for spark at the plugs with an old inductive pickup timing light on each of the 8 plug wires while the engine is running. Would it indicate a good coil pack if I got a steady timing light flash on each of the plug wires?

Thanks,
Tom Koenig
Riverside, IL

 

[teeman914]

I replaced the wires and plugs with a new Motorcraft set.

Still the P0352.

I read in another forum entry that the B coil comes on a few seconds after the initial start up. This is consistent with the way the code appears - a few seconds after start up. I usually clear the code after it appears each time. It does not reappear as long as the truck is running.

The truck does run well and all 8 plugs are firing - smooth idle, good acceleration, smooth cruise speed. I've hooked up an inductive timing light to each of the 8 wires while it is running and it fires the timing light on all 8 wires.

There just seems to be problem with that initial B coil test the PCM does at start up. Maybe there needs to be a new coil in that be position (I have flipped the coils and it still indicates a B coil malfunction). I'm going to get a new coil and try that.

After that I will try to do a more detailed test of the wire harness. I will have to unwrap the wire harness that goes into the PCM and find the pin position of the tan / lt blu wire (terminal 78) and the tan / lt grn wire (terminal 104). These are the B coil control wires. I'll check for continuity between the PCM plug and the coil pack plug. There doesn't seem to be anywhere along the length of the wire harness where there is a kink or any chaffing. The PCM pins are straight and shinny (new looking) - no dirt or corrosion of any kind. The plugs at the coil pack are also straight and shinny. I did use some dielectric grease when reinstalling. I don't think that's an issue.

I will report back after I try these fix attempts.

Thanks,
Tom Koenig
Riverside, IL

 

[teeman914]

1996 2.3L pcm terminal diagram

Does anyone have the pcm 104 terminal diagram for a 1996 2.3L? I got a partial one that describes pin 1 through 35.

Also, would it be alright to attempt to start my truck with one of the coils disconnected. I know that the A coil fires from initial ignition on but, the B coil starts firing several seconds later. I just want to be sure about the B coil position. It is what's the cause of my P0352 code.

Thanks,
Tom Koenig
Riverside, IL

 

[adsm08]

 

[teeman914]

I didn't work on the Ranger over the winter, but now that it's nice outside I've been try to track down this pesky P0352 code. I'll report all the things I've done later, but for now I did find a weak short in maxi fuse 13 a 50 amp maxi fuse. It says it feeds the I.P. fuse panel. I'm assuming that is the fuse panel inside the driver door on the left side of the dash. I did pull all the fuses in that panel and it did not make the test light go out. I had the test light connected between the negative battery cable and negative post of the battery. The test light did go out when I pulled the 50 amp fuse in position 13 in the power distribution box under the hood.

Any thoughts would be appreciated.

Thanks,
Tom