P0351, P0352, P0353 CEL

[Don Soriano]

RE: 1999 Ford Ranger XLT, V6, 4.0L Vin X.
The past month I started experiencing rough idle, jerking situation at various speeds and lack of power under load like going up hill. Otherwise no problem starting and no problem conking out on the road. However CEL indicates the following: P0351, P0352, P0353 indicating problem with the Primary/Secondary Ignition circuit.
I replaced the Ignition Coil, all 6 spark plugs and associated wires. That corrected the idling and performance problems. The vehicle runs great however, the CEL codes kept appearing despite erase.
I benched check the ignition coil and it tested good according to OEM parameters. Can I keep using my truck even with the CEL codes on? Or is there something else that need checking.
I appreciate any input.

Don

 

[RonD]

P0351 Ignition Coil A Primary/Secondary Circuit Malfunction
P0352 Ignition Coil B Primary/Secondary Circuit Malfunction
P0353 Ignition Coil C Primary/Secondary Circuit Malfunction

V6 Coil packs just have 3 coils inside, so getting these 3 codes means it something they have in common

The coil pack will have 4 wires, A, B, and C coils, and a 12volt wire<<should be red/green stripe
Key on
Test the battery voltage(with key on) so you have a baseline, 12.3-12.8volts is expected
Then test the red/green wire, should be EXACTLY the same
The 3 coils in the coil pack share this 12volt wire, it comes from fuse 19 in the cab fuse box

 

[DILLARD000]

Possible bad\shorted IgnitionNoiseSuppressionCapacitor?
Cap hotside spliced on the common 12v Ignition Coil wire in the harness
& groundside usually bolted to the CoilPack frame.

 

[Don Soriano]

P0351 Ignition Coil A Primary/Secondary Circuit Malfunction
P0352 Ignition Coil B Primary/Secondary Circuit Malfunction
P0353 Ignition Coil C Primary/Secondary Circuit Malfunction

V6 Coil packs just have 3 coils inside, so getting these 3 codes means it something they have in common

The coil pack will have 4 wires, A, B, and C coils, and a 12volt wire<<should be red/green stripe
Key on
Test the battery voltage(with key on) so you have a baseline, 12.3-12.8volts is expected
Then test the red/green wire, should be EXACTLY the same
The 3 coils in the coil pack share this 12volt wire, it comes from fuse 19 in the cab fuse box

Is it possible to have those CEL codes and not detecting any apparent operation or performance problems with the vehicle? At present I continue to use the vehicle. Is it also possible for certain ignition coil brands to be incompatible with certain PCMs which cause them to emit the codes? The ignition coil I replaced was the original Motorcraft which came with the vehicle. When I tested it one of the the primary circuits was open which is why I replaced it. Thanks for the response RonD.

 

[DILLARD000]

OhmCheck both your old & new CoilPack.
Whats the Make#Model of new CoilPack?

 

[RonD]

The one bad coil in the pack shouldn't have caused all 3 codes

Yes, good call DILLARD000, try unplugging the Noise Suppressor, its not required for engine operation, just AM radio operation, lol

Yes, unless the CEL starts to flash its fine to drive the vehicle
Flashing CEL means "back off the gas pedal"

Each coil gets the shared 12volts with key on
The 12volts pass thru each coil, and computer can "see" the 12volts on each coil's wire
Each time computer unGrounds a coil to spark it, it will see a voltage spike, if its a good "spark"

I would clear the codes each time they come back, after testing volts and unplugging the Noise Suppressor
This could be a computer issue if they keep coming back

 

[Don Soriano]

I took it to a reputable car mechanic and he upgraded the PCM. The same codes keep coming back after each erase. Is there a way to check if it's caused by the computer. Except for the CEL coming on, the vehicle runs great.

 

[DILLARD000]

What does "upgraded the PCM" mean exactly?

 

[RonD]

Did you unplug the Noise Suppressor?
Just that one wire capacitor bolted to coil pack

Looks like this: https://cdn2.bigcommerce.com/server1100/9194a/products/3993/images/22894/P1012446__84320.1465403514.1280.1280.JPG?c=2

Just unplug it

 

[Don Soriano]

What does "upgraded the PCM" mean exactly?

Some kind of adjustment of sorts I was told that car computers need.

 

[Don Soriano]

Did you unplug the Noise Suppressor?
Just that one wire capacitor bolted to coil pack

Looks like this: https://cdn2.bigcommerce.com/server1100/9194a/products/3993/images/22894/P1012446__84320.1465403514.1280.1280.JPG?c=2

Just unplug it

It never had the noise suppressor.

 

[RonD]

If it has the plug in for one then get it and bolt it to coil bolt and plug it in

 

[Don Soriano]

The one bad coil in the pack shouldn't have caused all 3 codes

Yes, good call DILLARD000, try unplugging the Noise Suppressor, its not required for engine operation, just AM radio operation, lol

Yes, unless the CEL starts to flash its fine to drive the vehicle
Flashing CEL means "back off the gas pedal"

Each coil gets the shared 12volts with key on
The 12volts pass thru each coil, and computer can "see" the 12volts on each coil's wire
Each time computer unGrounds a coil to spark it, it will see a voltage spike, if its a good "spark"

I would clear the codes each time they come back, after testing volts and unplugging the Noise Suppressor
This could be a computer issue if they keep coming back

I kept clearing the code using my OBD II but they kept coming back. Isn't there a way to erase the code by disconnecting the battery. BTW I removed my ignition coil and checked it out with a multimeter with results as follows:

LoV Pins B+ Pin 1 1.8 Ohms , B+ Pin 2 1.9 Ohms , B+ Pin 3 1.8Ohms
HiV Pins Between Pins 1 & 5 13.56KOhms, Pins 2 & 6 13.3KOhms, Pins 3 & 4 13.4KOhms

I reinstalled the ignition coil but the 3 same codes kept coming back. Otherwise the vehicle runs great. Let me know some other way to erase the CEL.

 

[RonD]

Get the capacitor and hook it up

No, the only way to clear codes is to either fix the problem or used an OBD2 reader
Unhooking battery will clear active codes but they will stay in memory, and CEL will come back on usually within a few minutes of warm up

Coil pack test looks fine but you can only test for a bad coil, not a good one
Coils work at such low impedance that when at operating temp(HOT) they can still fail, and test fine when not in use
So you can test if a coil is bad, but there is NO TEST for a good coil, except by using it

And the chance of 3 bad coils in a coil pack are pretty much 1 in a trillion billion, lol, unless its physically damaged

The 3 codes means its something external and shared by all 3 coils in the pack

Like the 12volts
The capacitor<<<<<noise supressor, this also "smooths" the 12volts
Or the Computer

 

[Don Soriano]

Get the capacitor and hook it up

No, the only way to clear codes is to either fix the problem or used an OBD2 reader
Unhooking battery will clear active codes but they will stay in memory, and CEL will come back on usually within a few minutes of warm up

Coil pack test looks fine but you can only test for a bad coil, not a good one
Coils work at such low impedance that when at operating temp(HOT) they can still fail, and test fine when not in use
So you can test if a coil is bad, but there is NO TEST for a good coil, except by using it

And the chance of 3 bad coils in a coil pack are pretty much 1 in a trillion billion, lol, unless its physically damaged

The 3 codes means its something external and shared by all 3 coils in the pack

Like the 12volts
The capacitor<<<<<noise supressor, this also "smooths" the 12volts
Or the Computer

I'll install the capacitor. The ignition coil must be OK since the vehicle is running good. Guess I'll just wait until something else comes up. Thanks