My dad has a 1997 LDF250 with 5.4. He got these codes po354, po355, po356, & po358 (coil circuits 4,5,6, & 8). Coils check ok and the hot in run circuits all have battery voltage.
I just want to make sure I am on the right track. I would like to test the ground circuit but I do not have a noid light. Will a test light work?

According to the wiring diagram, the inputs affecting these four coils, also affect the remaining four. Seems to reason, the inputs to the pcm would not be at fault, since the other coils are firing. Also seems to reason, if the ground circuit between the coils and pcm are ok, the pcm would be at fault?

If the pcm needs to be replaced, does it require any special programing?

Thanks!

 

The coils are grounded in the PCM by 8 solid state switches that are operated according to the fire order, unless it is done differently on that F250 model and year.
There is battery through a fuse standing on all the coils waiting for the grounds in the fire order sequence.
You can either use a noid light to see if the PCM is grounding the coils, or a good sensitive clamp-on timing light around the coil feeds to see solid high voltage triggered flash..
A look back toward the PCM switches on the coil leads will detect a faulty switch where a min and max resistance should be seen, 'not' an open or a short to ground.
If the PCM has to be replaced, programing needs to be done in accordance with the original build and any PCM related options..
A dealer looks up the program version from an as built FORD data base using your VIN number and down loads it for install into the replacment PCM unless they have a copy already stored.
Be awhere that the cats may be melted if you see CODE 420 along the way, later.
Good luck.

 

I finally got to do some more testing. Checked it with a noid light and confirmed my suspicions. The PCM/ECU is not grounding those four coils. I called the local dealer and this part has been discontinued. He suggested I call NAPA.

NAPA has remanufactured ECU's for $154 + tax. According to NAPA's descrption, it is compatable with all (MLC-211), whatever that is. This number is on the ECU that is in the truck now. Wondering if these are factory ECU's that have been remanufactured, since they have a core charge?

I also found a couple used ECU's for about the same price. Now I need to decide which one to get. Reman or used?

Anyone have experience with the remanufactured ECU's like NAPA sells?

Thanks!

 

Have you checked for the possability the harness plug has an issue?
Is there 13 volts standing on the coil feeds, from the fuse with the key on?.

 

The power circuits do have 12+ volts. The only thing I have not checked is continuity of the ground circuits, between the coils and ECU. I will check this before buying an ECU. I have only had a few minutes at a time to work on it. I should have time to check continuity tomorrow.

 

Finally have time to give an update. I got the remanufactured ECU from NAPA, $154 + core charge. Through a friend, I was able to borrow the equipment for programing purposes. Long story short, we found out that vehicles without anti theft keys, do not need programing. Just swap the ECU and go. The ECU solved the misfire.

 

Let me tell you, you got out of the issue cheap.
Without help from friends in right places, you would have been in for a hassle over added costs.
Watch for more code telling you the cats and/or Ox sensors might be a further issue as a result of the PCM failure.
If so replace them without even blinking an eye because there is nothing that can be done about it, otherwise.
Good luck.