1999 Dodge Stratus PCM burning ignition coil

Tiny
DFCT
  • MEMBER
  • 1999 DODGE STRATUS
Computer problem
1999 Dodge Stratus 4 cyl Front Wheel Drive Automatic

Hello,
my Stratus has a pack os 2 ignition coil, which is fed through three wires. Wire #1 is for the coil #1 signal (ground), wire #2 is the ASD relay output (always have voltage with the car on), and wire #3 is for the coil #2 signal (ground).

The problem is, wire #1 is constantly grounded, therefore keeping the coil always energized, which end's up melting.

I have tested everything, and problem is at the PCM. Also, checked for continuity at PCM pins "coil #1 signal" and "ground", and there's always around 25ohms resistance between them.

I don't know how it's inside the PCM, but could this be a short, a defective chip?

Do you know the exact location inside the pcm to look? Any tips on how to fix?

Thanks!
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Monday, December 29th, 2008 AT 9:11 AM

4 Replies

Tiny
JDL
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Monday, December 29th, 2008 AT 1:14 PM
Tiny
DFCT
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Code given was P0351 ("Ignition coil no. 1 primary circuit fault").

PCM should send signal (close the circuit) to coil #1 esporadically, and not always like it is now. (Just to mention, coil driver #2 is perfect).

So with engine running, coil driver #1 is sending constant signal (ground), which keeps the coil always energized.

If I disconnect the PCM connector, there's no more ground at the coil harness.
Also I checked the wiring extensively, and there's no short in it.

At the PCM, there's the following pins:
PIN 03 - coil #2 driver
PIN 10 - ground
PIN 11 - coil #1 driver

I don't know how the PCM is supposed to work, if it take's the ground to send to the coil from PIN 10. But the thing is, when I check with an ohmmeter directly at the pins, there's continuity between PINS 11-10, while there's NO continuity between PINS 03-10.
So, if PCM takes the ground from pin 10 (to send to the coil), probably the coil controller chip went bad. But if it takes from somewhere else, it could be only a short to ground inside the module.

I already opened the module, but it's kinda hard to trace the pins - there's MUCH compound over it all (like a sylicone). So if someone have a PCM service manual or knows exactly where to look, it would be a lot helpful.

Thanks !
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Monday, December 29th, 2008 AT 2:17 PM
Tiny
JDL
  • EXPERT
If terminal 10 to chassis ground, is the end ground for both coil drivers, then a problem on that circuit would kill both coils.

My info shows three ecm chassis grounds, it doesn't show what the grounds are for, but all three go to the same splice.

If the computer has a manufacturers tag on it, they may have a web site, and can give info on it.
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Monday, December 29th, 2008 AT 4:19 PM
Tiny
DFCT
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Hey guys
just to let you know.

I've traced the short inside the PCM, and the problem is at a MOSFET. It's made by motorola, and really hard to find. Can't even find a datasheet for it.
So I got a similar mosfet today, going to install it tomorrow and test. Hope it works!
If it runs fine, I guess I will switch ignitions's 2 mosfet also (it's the same motorola); so I dont get a similar problem soon.

@jdl123
there's only a label in it, and it only says Chrysler with the p/n. =(
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Wednesday, January 7th, 2009 AT 12:11 AM

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