I've got a 1999 Ram 1500, 5.9l gas engine with no power going to the #6 injector (engine running). I've traced wires from injector to PCM and both are intact. I back probed both wires from PCM connector 3 pin 12 for ground and connector 2, pin 12 for power (5 v). DVOM and NOID showed no power going to injector. I back probed injector #4 and NOID flashed on/off just to check my procedure. The only code that comes up with an OBDII scan is P206; open circuit of #6.

Is this identifying a lost injector driver in the PCM? If so can this be "flashed/reprogramed" or is a replacement PCM in order. If not a lost driver what am I facing? Any help would be greatly appreciated.

 

IIRC, the ASD relay powers the injectors and the PCM grounds them. Take a test light and hook the lead to a 12v source and probe the injector plug, one of the wires should make the test light flash while the engine is running. The other wire (green/orange?) should obviously have 12v continuously while the engine is running. If the injector simply isn't getting 12v it's a wiring problem somewhere, if it's not getting grounded and the wire is good to the PCM it has to be a PCM issue.

 

Hahns5.2,

Thanks so much for the response. I checked all 4 wires of my ASD (three to PCM and one to fuse in PDC) for continuity and they are all good. The continuity from my ground and power of my injector plug are all good back to the PCM as well.

I hooked a jumper wire from the battery positive side to my test light. Engine running, I connected that to my brown/blue power wire in the injector plug and no light at all. I kept that wire to the power side and connected the test light ground to the ground side of the connector (green/orange) and still no light. I tested the light on the battery and burned bright

So my ground from plug to PCM is good, my power side to PCM is good, all wires from ASD are good but still cannot get my light to fire when wired direct from battery to power of injector plug.

It seems everything is available to work right but no power from ASD or PCM to injector plug. Is this indicitive of a lost injector driver in the PCM?

Thanks.

 

Are you getting 12 volts TO the injectors?

Can you get the flashy signal from the test light on another injector? (just to verify that it will indeed react fast enough.)

 

All other 7 cylinders are firing and getting fuel and voltage. OBD II throws on code; P206 open circuit on #6 Injector. So if it is the only cylinder not getting voltage/electric, where would I look now? PCM possible. If it is the PCM can an injector driver be re-intalled thru a flash or does the entire PCM need to be wipped/cleared and a re-program done?

 

Injectors get power on the Dark Green with Orange trace wire. If there isn't power there, that's going to be at least part of the problem. Since all the other injectors are working, should be a short trace to where the problem is. (all common source from the ASD relay.)

If you can manage to get power to it, (or, you already are...) and the wire from the injector to the PCM tests good, and it still doesn't wanna work, then the PCM is going to be at fault, and it will require replacement to fix it.

 

Typical injector firing length is about 5ms long. I don't know if that's enough time for the bulb to react.

 

It was when I tried it

 

Alright, i'll stand corrected on that.

 

Thanks to all for your responses. I've traced every wire, continuitied every wire, tested relays, fuses, and cannot find a short or open circuit. I cannot get any voltage reading at the injector plug, yet both wires are intact (no short). I just can't get any power reading using my DVOM at the injector plug. So I'm guessing the PCM has "lost the injector" and does not recognize it. Final question is
1. Iff a flash would re-install the injector or do I need the PCM to be reprogramed.
2. If flashing/reprogramming will not work then I'm gusying I will need a new/refurbished PCM.