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View Full Version : LB7 low voltage to injector#1 -Dead Miss


HTRN
06-17-2014, 19:48
I have a 03 LB7 200K with low voltage (0.3v) to injector # 1. Others have between 4 & 9V. Wiring harness checks good, all injector including #1 ohm out the same. Anyone heard of this? Suggestions? I'm thinking FICM replacement.
DmaxMaverick
06-17-2014, 20:22
If you find nothing downstream of the FICM (and it appears you didn't), then it sounds like you lost a driver, which makes the FICM the likely suspect. What DTC's are you seeing? PWM dwell? Balance rates? #1 should be off the scale.
HTRN
06-18-2014, 13:31
The only code I have is for glow plug.

I do not have anything to tell me the rest of the data. I checked the voltage and resistance from the upstream side of the injector plugs with the truck running.
DmaxMaverick
06-18-2014, 14:11
You really need the diagnostic data. Without it, you won't know if the FICM has failed, or if the PCM is commanding the voltage. If it does in fact have a "dead miss", it should be detected by the PCM, and it should attempt to compensate. If it fails to compensate, it should then set the MIL, and associated DTC's should be present. It would also likely set Limp Mode (reduce power and RPM).

Which "glow plug code"? If it's only P0380, it won't affect any other system operation. Other GP codes may, depending on the emission system region programming.

If you have ANY aftermarket program/programmer or power adder installed, it should be removed (physically) before attempting any diagnosis. More often than not, that alone "cures" issues such as this.
Kennedy
06-19-2014, 07:18
If you are "tapping" to get the voltage wouldn't it be possible that the injector in question has a short that is draining the voltage? Electrical is not my strong suit, but we seldom see the FICM go bad although a lot of people replace them (wishful thinking) with no change.

I have heard them fail dropping entire injector groups.
HTRN
06-23-2014, 23:50
PO380 is the only code.

I checked voltage on both sides of injectors and checked harness for short to ground and continuity.

I agree I need the data, any suggestions on best diagnostic tool to purchase?
Kennedy
06-24-2014, 10:16
OK let's make sure I'm following this correctly:

1) You have a dead miss on one cylinder and no/low voltage to the injector in question

2) The only DTC present is P0380 glow plug feedback?


The next thing I'd be looking at is what the balance rate is for the injector in question.

I would assume that it would be +15.