Noid light stays on, code 27
#1
01-11-2015, 04:21 PM
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Noid light stays on, code 27
I have a 1995 dakota 3.9 automatic with 120000 miles. I have an intermittent problem with code 27. 25% of my time driving the truck it works fine. The other 75% of time my truck runs really rough, like it's running on 4 or 5 cylinders. It also stalls sometimes when I'm coming to a stop. The check engine light is also on. Sometimes during this time white smoke comes out tailpipe, and smells heavily like gas.
I used a noid light test on all cylinders, all but the #6 cyl flashed correctly. #6 keeps the noid light on at all times. What would cause the noid light to stay on all the time? This is an intermittent issue, happens 75% of the time. Thanks
I used a noid light test on all cylinders, all but the #6 cyl flashed correctly. #6 keeps the noid light on at all times. What would cause the noid light to stay on all the time? This is an intermittent issue, happens 75% of the time. Thanks
#3
01-12-2015, 09:18 AM
Champion
Since most injectors fire by the ECU grounding (i.e., 12V hot all the time the ASD is engaged, ECU grounds the return to fire), it could be a bad wire (grounding the - side), or a bad ECU.
I'd a) disconnect the battery, b) check for continuity to ground from the - side of that injector, then c) disconnect the PCM and d) repeat b.
If the continuity stays, you've got bad wiring. If it goes, your PCM is hanging, and you'll probably need a new PCM.
RockAuto lists them, but the local boneyard is a LOT cheaper.
RwP
I'd a) disconnect the battery, b) check for continuity to ground from the - side of that injector, then c) disconnect the PCM and d) repeat b.
If the continuity stays, you've got bad wiring. If it goes, your PCM is hanging, and you'll probably need a new PCM.
RockAuto lists them, but the local boneyard is a LOT cheaper.
RwP
#4
01-12-2015, 06:32 PM
Join Date: Dec 2014
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Disconnected battery
So I disconnected the positive and negitive wires to battery. I tested for continuity at problem injector harness, it's good. I then disconnected PCM harness and repeated the test and I still got continuity. This means a bad wire? is there somewhere I should start troubleshooting for a bad wire?
Thanks for taking the time to help
p.s. I bought a new PCM a month ago and it did not solve my problem
.QUOTE=RalphP;3219753]Since most injectors fire by the ECU grounding (i.e., 12V hot all the time the ASD is engaged, ECU grounds the return to fire), it could be a bad wire (grounding the - side), or a bad ECU.
I'd a) disconnect the battery, b) check for continuity to ground from the - side of that injector, then c) disconnect the PCM and d) repeat b.
If the continuity stays, you've got bad wiring. If it goes, your PCM is hanging, and you'll probably need a new PCM.
RockAuto lists them, but the local boneyard is a LOT cheaper.
RwP[/QUOTE]
Thanks for taking the time to help
p.s. I bought a new PCM a month ago and it did not solve my problem
.QUOTE=RalphP;3219753]Since most injectors fire by the ECU grounding (i.e., 12V hot all the time the ASD is engaged, ECU grounds the return to fire), it could be a bad wire (grounding the - side), or a bad ECU.
I'd a) disconnect the battery, b) check for continuity to ground from the - side of that injector, then c) disconnect the PCM and d) repeat b.
If the continuity stays, you've got bad wiring. If it goes, your PCM is hanging, and you'll probably need a new PCM.
RockAuto lists them, but the local boneyard is a LOT cheaper.
RwP[/QUOTE]