P0202 - Injector Circuit Open

[BenWranGo]

Hi All,

As a '99 manual 4.0 TJ owner of 3 months I have had more cause to use this forum than I would have liked. But great resource guys, thank you!

I took the Jeep for a service and while there it started misfiring and throwing the above error. Open injector circuit on the second cylinder. Error appears to be related to the signal on the control wire, and injector is effectively permanently injecting; running rough and fuel spitting out the exhaust. So, I bought the wranglerfix PCM. Same issue immediately.

So this weekend i tried the below:

• I traced the wiring back to the pcm, no obvious signs of damage
• Tried bypassing most of the control wire by cutting an inch out from the pCM and splicing a new wire in to an inch out of the injector pigtail
• Swapped out the pigtail
• Swapped out the injector
• Swapped fuses

None of the above solved the problem, although interestingly when playing with the +ve wiring (there was an old repair using a heatshrink sleeve i removed) i managed to replicate the issue on two other injectors. (i fixed this when I re-spliced the +ve wire)

What else would you all look at next!? i'm running out of ideas!


I guess If there was some kind of short in the injector #2 circuit could I have fried the new PCM straight away!? I'm in the UK so hoping not to have send stuff back and forth too much.

Thanks in advance!

Ben

 

[Chris]

Hi All,

As a '99 manual 4.0 TJ owner of 3 months I have had more cause to use this forum than I would have liked. But great resource guys, thank you!

I took the Jeep for a service and while there it started misfiring and throwing the above error. Open injector circuit on the second cylinder. Error appears to be related to the signal on the control wire, and injector is effectively permanently injecting; running rough and fuel spitting out the exhaust. So, I bought the wranglerfix PCM. Same issue immediately.

So this weekend i tried the below:

• I traced the wiring back to the pcm, no obvious signs of damage
• Tried bypassing most of the control wire by cutting an inch out from the pCM and splicing a new wire in to an inch out of the injector pigtail
• Swapped out the pigtail
• Swapped out the injector
• Swapped fuses

None of the above solved the problem, although interestingly when playing with the +ve wiring (there was an old repair using a heatshrink sleeve i removed) i managed to replicate the issue on two other injectors. (i fixed this when I re-spliced the +ve wire)

What else would you all look at next!? i'm running out of ideas!


I guess If there was some kind of short in the injector #2 circuit could I have fried the new PCM straight away!? I'm in the UK so hoping not to have send stuff back and forth too much.

Thanks in advance!

Ben

Make sure that your ground connections specifically for the fuel injectors are solid. A poor ground can cause all sorts of electrical issues and could mimic an open circuit.

While you’ve looked back at the PCM, it’s worth tracing the entire injector harness back to the main wiring harness to spot any wear, chafing, or corrosion that might not be immediately visible. Sometimes the issue can be further down the line.

Using a multimeter, check the voltage at the injector while cranking the engine. You should see a voltage pulse if the PCM is trying to activate it. If there’s a consistent 12V without a pulse, the control signal may not be reaching the injector.

Besides checking the injector ground, ensure that the PCM itself has a good ground. Faulty grounds at the PCM can lead to strange behavior, including inability to control the injectors properly.

Inspect the connector pins for any corrosion or bent connections at both the PCM and injector harness. Sometimes just reseating the connectors can resolve intermittent issues.

You mentioned a short could have potentially damaged the new PCM. It’s definitely a possibility, especially if there was an existing issue that wasn't resolved. If you have the ability, consider using a circuit tester to confirm there aren't any unexpected shorts in the wiring.

If you have access to a scan tool with more capabilities, try monitoring the injector pulse width and related parameters while the engine is running. This can give insight into what's happening during operation.

As for the possibility of getting the PCM fried, it is conceivable if there was a significant short somewhere in the injector circuit. If you determine it's a wiring issue, you may want to inspect the circuit further before installing another new unit.

Hopefully, some of these suggestions lead you closer to a solution.

 

[jjvw]

Hi All,

As a '99 manual 4.0 TJ owner of 3 months I have had more cause to use this forum than I would have liked. But great resource guys, thank you!

...

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