P0204 - JeepForum.com
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post #1 of 13 Old 06-14-2019, 04:58 AM Thread Starter
99WJ539918
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P0204

2000 WJ 4.7L
P0204 (and subsequently P0304) popped up today. I checked for continuity between the injector pins and had 15 ohms (engine was warm). I checked for continuity between the injector plug and pin 16 of the white connector on the PCM and had 0.02 - 0.06 ohms. Before I start swapping injectors between cylinders, isn't this a TPS issue? I remember something from years ago about this and wanted to make sure before I went any farther. Thanks.

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post #2 of 13 Old 06-14-2019, 06:57 AM
jtec
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I would concentrate on wiring first.
Yes this could be a pcm driver issue but lets work it before going there.

A noid light makes this easier, check #4 connector* and wiggle harness to see if noid changes (on soild wont flash) 15ohms seams high BUT i would confirm spec with manuals...

*my first suspect

PS - send a PM to 'waterluvr' he is the PCM guru and will advise if we end up at driver issue...

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #3 of 13 Old 06-14-2019, 07:36 AM
jtec
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FWIW

Disconnect the fuel injector wire harness connector
from the injector. The injector is equipped with 2
electrical terminals (pins). Place an ohmmeter across
the terminals. Resistance reading should be approximately
12 ohms 61.2 ohms at 20C (68F).

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #4 of 13 Old 06-14-2019, 08:47 AM
Mattyjm
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Found this. It's a TSB on the 4.7L V8.

Multiple injector circuit codes. MIL on, no noticeable driveability problems. May have code P0121 - TPS voltage does not agree with MAP. Possible codes P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208
System:
Emissions/PCM/Fuel
Codes:
P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208
Problem:
The PCM software falsely sets injector circuit codes when there is really no problem with the injectors. The problem is voltage spikes from the Throttle Position Sensor.
Test & Fix:
Throttle Position Sensor (TPS) voltage spikes greater than 0.02 volts trigger these false codes. Theoretically, this could be caused by an intermittent ground or other wiring connection. However in actual practice it is almost always a problem with the TPS itself. Due to the nature of this problem there is no conclusive way to test the TPS or the TPS circuit. If there are multiple injector circuit codes with no misfire, replace the TPS and clear the codes.
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post #5 of 13 Old 06-14-2019, 09:57 AM
Waterluvr
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Quote:
Originally Posted by jtec View Post
I would concentrate on wiring first.
Yes this could be a pcm driver issue but lets work it before going there.

A noid light makes this easier, check #4 connector* and wiggle harness to see if noid changes (on soild wont flash) 15ohms seams high BUT i would confirm spec with manuals...

*my first suspect

PS - send a PM to 'waterluvr' he is the PCM guru and will advise if we end up at driver issue...
This is good place to start, that area of the harness is a known problem with the #4 circuit, and don't overlook the TPS voltages get a liva data scanner on it and graph voltage fluctuations as you change rpm's and TPS angles this image is taken at idle but you will see voltage fluctuations on the graph as you raise and lower the rpms.





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post #6 of 13 Old 06-14-2019, 10:13 AM Thread Starter
99WJ539918
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Quote:
Originally Posted by jtec View Post
FWIW

Disconnect the fuel injector wire harness connector
from the injector. The injector is equipped with 2
electrical terminals (pins). Place an ohmmeter across
the terminals. Resistance reading should be approximately
12 ohms 61.2 ohms at 20C (68F).

I checked that and had 15 ohms. My engine was still warm because I just got home.

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post #7 of 13 Old 06-14-2019, 10:14 AM Thread Starter
99WJ539918
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Quote:
Originally Posted by Mattyjm View Post
Found this. It's a TSB on the 4.7L V8.

Multiple injector circuit codes. MIL on, no noticeable driveability problems. May have code P0121 - TPS voltage does not agree with MAP. Possible codes P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208
System:
Emissions/PCM/Fuel
Codes:
P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208
Problem:
The PCM software falsely sets injector circuit codes when there is really no problem with the injectors. The problem is voltage spikes from the Throttle Position Sensor.
Test & Fix:
Throttle Position Sensor (TPS) voltage spikes greater than 0.02 volts trigger these false codes. Theoretically, this could be caused by an intermittent ground or other wiring connection. However in actual practice it is almost always a problem with the TPS itself. Due to the nature of this problem there is no conclusive way to test the TPS or the TPS circuit. If there are multiple injector circuit codes with no misfire, replace the TPS and clear the codes.

This might be what I was remembering. Thanks... I've been out of the WJ game for a while, where's the best place to buy a Mopar TPS? Thanks.

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post #8 of 13 Old 06-14-2019, 10:15 AM Thread Starter
99WJ539918
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Quote:
Originally Posted by Waterluvr View Post
Quote:
Originally Posted by jtec View Post
I would concentrate on wiring first.
Yes this could be a pcm driver issue but lets work it before going there.

A noid light makes this easier, check #4 connector* and wiggle harness to see if noid changes (on soild wont flash) 15ohms seams high BUT i would confirm spec with manuals...

*my first suspect

PS - send a PM to 'waterluvr' he is the PCM guru and will advise if we end up at driver issue...
This is good place to start, that area of the harness is a known problem with the #4 circuit, and don't overlook the TPS voltages get a liva data scanner on it and graph voltage fluctuations as you change rpm's and TPS angles this image is taken at idle but you will see voltage fluctuations on the graph as you raise and lower the rpms.






I'll check the TPS voltage readings when I get home and report back. Thanks.
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post #9 of 13 Old 06-14-2019, 04:28 PM Thread Starter
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I switches the #4 and #2 injectors and almost immediately a P0202 came on. I'll go to a junkyard and snag an injector tomorrow. Unless one from my 99 4.0L would work...?

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post #10 of 13 Old 06-14-2019, 08:11 PM
Mattyjm
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Quote:
Originally Posted by 99WJ539918 View Post
I switches the #4 and #2 injectors and almost immediately a P0202 came on. I'll go to a junkyard and snag an injector tomorrow. Unless one from my 99 4.0L would work...?
You'll have to cross-reference part numbers but there's a pretty good chance that it would work. Is your '99 not running?

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2004 Rocky Mountain Edition. Froggy Bandit. Wife's Daily Driver. PRISTINE! Stock height and may stay that way.....
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post #11 of 13 Old 06-14-2019, 08:39 PM Thread Starter
99WJ539918
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Quote:
Originally Posted by Mattyjm View Post
Quote:
Originally Posted by 99WJ539918 View Post
I switches the #4 and #2 injectors and almost immediately a P0202 came on. I'll go to a junkyard and snag an injector tomorrow. Unless one from my 99 4.0L would work...?
You'll have to cross-reference part numbers but there's a pretty good chance that it would work. Is your '99 not running?

It runs, I crashed it during the winter. I'm going to a junkyard tomorrow morning to grab a TPS and a fuel injector.

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post #12 of 13 Old 06-16-2019, 03:57 PM
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Good to hear that its looking like a injector fault and my electrical/computer.

https://r.tapatalk.com/shareLink?sha...5&share_type=t

I dealt with a blown driver / shorted wiring on my XJ. If other issues still keep up I documented my fix above. Good luck


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post #13 of 13 Old 06-21-2019, 06:21 PM Thread Starter
99WJ539918
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Forgot to post the outcome... I couldn't find a used injector at my local junkyard so I went with a new one. I've driven it about 75 miles and it all seems to be fine.
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