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sprinkles08
sprinkles08, ASE Certified Technician
Category: Chrysler
Satisfied Customers: 21601
Experience:  ASE Master & Advanced level certified, Chrysler Master Certified, Trans and Hybrid Specialist
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05 pacifica no power to 3 coils no communication to bcm

Customer Question

05 pacifica no power to 3 coils no communication to bcm j1850 short to ground. Checked all grounds added ground wire. Scratching head on this one
Submitted: 1 year ago.
Category: Chrysler
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

If there is no power to three coils it would have to be a wiring issue. All coils and fuel injectors are powered by the same circuit.

What are the actual symptoms you're trying to repair?

Customer: replied 1 year ago.
The vehicle runs barely on 3 cylinders pull the 3 rear coils off and it runs the same. Coils ohm out to be Ok at .8 ohms
Expert:  sprinkles08 replied 1 year ago.

You've used an incandescent test light with the engine running and found no voltage on the ASD wire at three coils?

Customer: replied 1 year ago.
I have not tried it that way yet I can do that and get back to you
Expert:  sprinkles08 replied 1 year ago.

Ok.

Customer: replied 1 year ago.
I'm not able to get to it till later tonight. Should there be a constant positive voltage there or negative. So what I'm asking is does it fire on the negative or the positive?
Expert:  sprinkles08 replied 1 year ago.

The coils and injectors receive constant powerffrom the ASD relay.

Customer: replied 1 year ago.
the coils do get power from the asd
Expert:  sprinkles08 replied 1 year ago.

I figured they did.

Are you able to communicate with the PCM with a code reader or scan tool?

Customer: replied 1 year ago.
i have a pretty decent launch scanner and that is where I got codes on the bcm with the no communication and the j1850 short to ground
Customer: replied 1 year ago.
Also get no communication with the ddm and pdm.
Expert:  sprinkles08 replied 1 year ago.

The module you're concerned with is the PCM. Are you able to communicate with it?

Customer: replied 1 year ago.
i do and it doesn't get a chance to get any codes cause it can never run long enough.
Expert:  sprinkles08 replied 1 year ago.

The engine doesn't need to run to set fault codes. When you're unplugging coils it's setting codes for those coil primary circuit. You'rs seeing those set?

Customer: replied 1 year ago.
I currently have a p0685 and a p0688. And when I pull the plugs off the coil it doesn't show up on scan tool
Customer: replied 1 year ago.
anything else I unplug shows on the scanner but unplugging the coils doesn't show up on the scanner
Expert:  sprinkles08 replied 1 year ago.

These are both for the ASD relay. Do these set on their own or were they a result of you having the relay out?

Customer: replied 1 year ago.
They may have set from me unplugging the relay. I was messing with it and now get a p2314 and p2308
Expert:  sprinkles08 replied 1 year ago.

Did these set on their own or as a result of unplugging coils?

Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 1 year ago.
I just hate to toss new coils at it when they ohm out in spec
Expert:  sprinkles08 replied 1 year ago.

Did these set on their own or as a result of unplugging coils?

Customer: replied 1 year ago.
I was unplugging coils when it was trying to run. Otherwise I don't get any codes
Expert:  sprinkles08 replied 1 year ago.

You set the codes yourself then.

Are you using an actual scan tool and can monitor data?

Customer: replied 1 year ago.
i can monitor all data using a launch x431
Expert:  sprinkles08 replied 1 year ago.

Is it counting misfires on any certain cylinders?

Customer: replied 1 year ago.
There is no negative pulse from the pcm for the 1 3 5 cylinders I opened the harness expecting to find a problem with the wires and they are just fine. Does the crank sensor send the pulse? Before suspect a bad driver in the pcm
Expert:  sprinkles08 replied 1 year ago.

The coil drivers in the PCM may have failed, the driver circuits could be shorted or open or it coudl possibly be a cam timing issue. If you unplug the cam sensor and start the engine are the drivers present?

Customer: replied 1 year ago.
I will give it a try tonight. I have to get a crank sensor seeing it didn't want to cooperate and broke off.
Expert:  sprinkles08 replied 1 year ago.

Let me know how it goes.

Customer: replied 1 year ago.
Well I got it out but would I love to have a talk with the dummy who designed that one. A simple oring rather then a size on size hole for a sensor would have saved many headaches.
Expert:  sprinkles08 replied 1 year ago.

That didn't fix the driveability issue did it?

Customer: replied 1 year ago.
Far from driveable only firing 3 cylinders
Expert:  sprinkles08 replied 1 year ago.

Try unplugging the cam sensor and then starting the engine to see if it's the same.

Customer: replied 1 year ago.
Unplugged cam sensor and motor runs a little different not good enough to move itself.
Expert:  sprinkles08 replied 1 year ago.

The next thing that should be done is test the coil driver circuits that aren't working for a short to ground and test their continuity from the coils to the PCM.

Customer: replied 1 year ago.
I have opened up the wire harness and tested the wires to the orange plug all 6 test out for good continuity. I have not checked them to ground I'm with the vehicle now so I will do that and let you know in a few minutes
Expert:  sprinkles08 replied 1 year ago.

Ok.

Customer: replied 1 year ago.
No connection to ground on any of the wires. All coils ohm at .8 from the orange plug and the asd relay
Expert:  sprinkles08 replied 1 year ago.

Are you able to see coil burn time in scan tool data? If so does it show these coils should be firing?

Customer: replied 1 year ago.
Not sure if my scanner can do that I have a ethos and a launch. But no keys for the ethos so chrysler is generic
Expert:  sprinkles08 replied 1 year ago.

Take a look and see if you're able to look at burn time.

Customer: replied 1 year ago.
Well after replacing the computer because of no output to coil 1&3. I got all coils firing but still ran like crap and turned the converter red hot. I pulled timing covers and found the belt had jumped a few teeth on the crank. Aligned timing marks back up and started motor and she started right up. Hope to get it all back together tonight
Expert:  sprinkles08 replied 1 year ago.

Great!

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