on my 99 dakota. It all started with some hesitation when the engine is cold, then the check engine light finally came on. Truck still runs so took it in got these codes and the mechanic pulled on some wires said they were good then said the problem was I needed to replace the PCM. But I have seen another thread on this site where people fixed the problem by replacing a TPS sensor, or Cam position sensor, or crank sensor and the problem went away. Any thoughts or experiences along with way would be appreciated.
jmfischer
I am having the same problrm with my 02 dakota check engine light only stays on for a couple minutes then goes away i was told by the owner that it had a bad tps wich i will be replacing soon
http://www.obd-codes.com/p0201
http://www.obd-codes.com/p0202
http://www.obd-codes.com/p0203
http://www.obd-codes.com/p0206
http://www.obd-codes.com/p0207
joes~a~user, I’m not sure how a sensor would effect the voltage reading on the fuel injectors circuit. They don't share power or ground or any other wires with the injectors in questions according to my '03 D's factory service manuals wiring diagrams. Don’t assume that your CEL is the same as jmfischer's. Get the codes read and continue to diagnose from there. Never assume...
These codes mean that the PCM detected a fault in the injector or the wiring to the injector. The PCM monitors the injector and when the injector is activated, the PCM expects to see the voltage pulled "low" or close to zero. When the injector is switched off, the PCM expects to see a voltage that is close to battery voltage or "high". If it doesn't see the expected voltage the PCM will set this code. The PCM also monitors resistance in the circuit. If the resistance is excessively low or high it will set this code.
I suspect the problem is either a wiring issue or a bad PCM. Most likely a wiring issue. If you have access to an oscilloscope this should be pretty easy to track down. You need an oscilloscope instead of a volt/multi-meter due to the speed at which the PCM adds/removes the ground from the injector. A multi-meter is too slow to completely diagnose it. However, a volt-multi-meter can get you pretty far. It can't, however, accurately determine if there is excessive resistance on the ground wire because the PCM is adding/removing the ground connection too fast. Ohm'ing the ground wire won't tell you much either because all wires have some amount of resistance. So without the proper ohm spec for the ground side you won't be able to tell what is acceptable and what is excessive. You could compare the ohm reading for one wire to another known good injector ground wire, but that isn't very accurate. So here is some simple tests you can do with a volt/multi-meter (keep in mind that there can be more then one problem):
First step in all electrical diagnostics is to get the battery voltage:
Next figure out which wire is power & which wire is ground. This will also test if the injector is getting power, if there is excessive resistance, break or short to ground in the power wire, if there is an internal break in the injector, if there is a break in the ground wire or if the injector is internally shorted or if the PCM is supplying a ground. Do not try to save time and use to back probes. If they touch you will cause a short which could easily cause a short and fry your PCM (or blow a fuse if your lucky).
If you get zero volts on both wires, then there is a break or short to ground in the power wire somewhere. Continue to “Test A"
If you get more then 0.5 volts below battery voltage on the power wire then there is excessive resistance on the power wire somewhere.
If you get zero volts on the ground wire, then there is an internal break in the injectors circuitry.
If you get constant battery voltage on both wires then either there is a break in the ground wire, or the injector is internally shorted or the PCM is not supplying a ground. Continue to “Test B"
Test A This assumes that you got zero volts on both wires above in which case you still don’t know which wire is power & which wire is ground so you have to test both wires. If you have the circuit diagram, you can just test the power wire if you want.
WARNING!!! If your injector wiring harness connector is a male connector make sure not to touch the meter leads metal tip to both pins at the same time. This will cause a short that could easily fry your PCM (or blow a fuse if your lucky)
If you still get zero volts on both wires, then the power wire is broken somewhere.
Test B This assumes that you got battery voltage on both wires, in which case you still don’t know which wire is power & which wire is ground so you have to test both wires. If you have the circuit diagram, you can just test the ground wire if you want.
WARNING!!! If your injector wiring harness connector is a male connector make sure not to touch the meter leads metal tip to both pins at the same time. This will cause a short that could easily fry your PCM (or blow a fuse if your lucky)
If you get between zero and 0.5 volts on both wires, then there is a break in the ground wire somewhere.
If you get between zero and 0.5 volts on one wire (the power wire) and constant battery voltage on the other wire (the ground wire) then the ground wire is shorted to power.
Pro-Tip: To find excessive resistance, a break in a wire, or a short to ground/power walk up the wire towards the battery until you get a reading you expect. The problem will be between the first point you got a good reading and the last point you got a bad reading.
Pro-Tip: Avoid poking wholes in wires. Back-probe connectors instead whenever possible. Poking wholes creates vectors for moisture to get into the wire and corrode it from the inside out resulting in more wiring issues down the road. But if you must poke wholes, remember to seal it up with
or heat shrink tubing if you feel like taking the connector apart in order to snake the heat shrink tubing over the wire(s).
Hope this helps… Let me know if you have any questions…
http://www.obd-codes.com/p0202
http://www.obd-codes.com/p0203
http://www.obd-codes.com/p0206
http://www.obd-codes.com/p0207
joes~a~user, I’m not sure how a sensor would effect the voltage reading on the fuel injectors circuit. They don't share power or ground or any other wires with the injectors in questions according to my '03 D's factory service manuals wiring diagrams. Don’t assume that your CEL is the same as jmfischer's. Get the codes read and continue to diagnose from there. Never assume...
These codes mean that the PCM detected a fault in the injector or the wiring to the injector. The PCM monitors the injector and when the injector is activated, the PCM expects to see the voltage pulled "low" or close to zero. When the injector is switched off, the PCM expects to see a voltage that is close to battery voltage or "high". If it doesn't see the expected voltage the PCM will set this code. The PCM also monitors resistance in the circuit. If the resistance is excessively low or high it will set this code.
I suspect the problem is either a wiring issue or a bad PCM. Most likely a wiring issue. If you have access to an oscilloscope this should be pretty easy to track down. You need an oscilloscope instead of a volt/multi-meter due to the speed at which the PCM adds/removes the ground from the injector. A multi-meter is too slow to completely diagnose it. However, a volt-multi-meter can get you pretty far. It can't, however, accurately determine if there is excessive resistance on the ground wire because the PCM is adding/removing the ground connection too fast. Ohm'ing the ground wire won't tell you much either because all wires have some amount of resistance. So without the proper ohm spec for the ground side you won't be able to tell what is acceptable and what is excessive. You could compare the ohm reading for one wire to another known good injector ground wire, but that isn't very accurate. So here is some simple tests you can do with a volt/multi-meter (keep in mind that there can be more then one problem):
First step in all electrical diagnostics is to get the battery voltage:
- Key on, engine off
- Set your meter to as close to 15 volts as possible, without going under
- Touch the negative lead on the meter to the negative battery post
- Touch the positive lead on the meter to the positive battery post
Next figure out which wire is power & which wire is ground. This will also test if the injector is getting power, if there is excessive resistance, break or short to ground in the power wire, if there is an internal break in the injector, if there is a break in the ground wire or if the injector is internally shorted or if the PCM is supplying a ground. Do not try to save time and use to back probes. If they touch you will cause a short which could easily cause a short and fry your PCM (or blow a fuse if your lucky).
- start the truck and let it idle
- Set your meter to as close to 200 volts without going under (the voltage will spike fairly high when the PCM removes the ground due to the collapse of the magnetic field inside the injector)
- back-probe one wire at the connector with a small safety pin
- Touch the negative meter lead to the negative battery post
- Touch the positive meter lead to the safety pin
- remove the safety pin from the back of connector
- back-probe the other wire at the connector with the safety pin
- Touch the positive meter lead to the safety pin
If you get zero volts on both wires, then there is a break or short to ground in the power wire somewhere. Continue to “Test A"
If you get more then 0.5 volts below battery voltage on the power wire then there is excessive resistance on the power wire somewhere.
If you get zero volts on the ground wire, then there is an internal break in the injectors circuitry.
If you get constant battery voltage on both wires then either there is a break in the ground wire, or the injector is internally shorted or the PCM is not supplying a ground. Continue to “Test B"
Test A This assumes that you got zero volts on both wires above in which case you still don’t know which wire is power & which wire is ground so you have to test both wires. If you have the circuit diagram, you can just test the power wire if you want.
WARNING!!! If your injector wiring harness connector is a male connector make sure not to touch the meter leads metal tip to both pins at the same time. This will cause a short that could easily fry your PCM (or blow a fuse if your lucky)
- Unplug the injector
- Touch the negative meter lead to the negative battery post
- Touch the positive meter lead to connector pin/whole for one wire
- Touch the positive meter lead to connector pin/whole for the other wire
If you still get zero volts on both wires, then the power wire is broken somewhere.
Test B This assumes that you got battery voltage on both wires, in which case you still don’t know which wire is power & which wire is ground so you have to test both wires. If you have the circuit diagram, you can just test the ground wire if you want.
WARNING!!! If your injector wiring harness connector is a male connector make sure not to touch the meter leads metal tip to both pins at the same time. This will cause a short that could easily fry your PCM (or blow a fuse if your lucky)
- Unplug the injector
- Touch the negative meter lead to the positive battery post
- Touch the positive meter lead to connector pin/whole for one wire
- Touch the positive meter lead to connector pin/whole for the other wire
If you get between zero and 0.5 volts on both wires, then there is a break in the ground wire somewhere.
If you get between zero and 0.5 volts on one wire (the power wire) and constant battery voltage on the other wire (the ground wire) then the ground wire is shorted to power.
Pro-Tip: To find excessive resistance, a break in a wire, or a short to ground/power walk up the wire towards the battery until you get a reading you expect. The problem will be between the first point you got a good reading and the last point you got a bad reading.
Pro-Tip: Avoid poking wholes in wires. Back-probe connectors instead whenever possible. Poking wholes creates vectors for moisture to get into the wire and corrode it from the inside out resulting in more wiring issues down the road. But if you must poke wholes, remember to seal it up with
Hope this helps… Let me know if you have any questions…
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