Morning guys and gals. So I have recently acquired an 02 chevy 2500hd ccsb lb7. Been sitting since last Sep/Oct with crank/no start. Pulling the codes once I got fresh batteries and bcm and that hooked back up. Took out an aftermarket (relay style) auto starter and cobbled in aftermarket radio. Those were the last things done to the truck to my knowledge beside new xfer case. Getting a p0090 and u1800. I'm pretty resourceful when I comes to mechanical work, and most electrical stuff, But I need some help trying to track down either a short or determining if the ficm is bad. As she sits, stock truck minus carter lift pump, she has 225ish psi on actual rail pressure. On my tech 2 desired is set around 5800psi? Can increase or decrease it, just where it was called out to. Just let the entire truck sit with no power or tcm, ecu or ficm hooked up for 24hrs. 100% fresh good fuses in fuse panel as well ($80 for all new fuses was crazy!) Cleaned all connections/wires and reinstalled last night to still no luck. GP cycles and all normal acting there. She does have a cluster issue with the dic displaying infor like "driver 1" and miles etc but that comes on after a few minutes of key on power being applied. I have to pull and work on the cluster still but that wouldnt keep the truck from running or give the no comms code would it? Only thing i dont have any information on is the bail connectors on the motor, i have some diagrams from a dmax manual but nothing else. Im trying to rule the harness out. I did swap ficms to what was a known good unit however the tech 2 states no connection still. Does the ficm have to be full installed, like on to motor and fuel lines? As I didn't do that just swapped connectors over to see if the tech 2 would see it. No blown fuses to ficm, injb 25amp. Pulled the entire harness for the ecu/tcm up and check it over in the common rub areas and dont see any freyed/broken wires, as i did with the ficm wires at the alternator to find nothing. Just unsure about the bale connectors? As i dont have any information on those, but no broken wires at the connectors visable. Is there something I need to be looking for? Any extra guidance would be greatly appreciated! She is currently sitting with ecu/tcm sitting by the fuse box for trouble shooting, but all sheathing has been remove towards connectora. New to the electronics game have an 85 k5 blazer with a 6.2/6.5 hybrid build and a s366 breathing fire on my custom resto-mod.
03 LB7 crank no start. No coms with ficm
- Thread starter bogema
- Start date
According to the tech 2 she's building good? pressure? Wouldn't let me send video, looks like it runs up to 15-16k Not sure what's needed to fire. Attach a video of the monitor. And no trying to pin the ficm and bale connectors is today's task. But limited on terminal schematics. Still researching the pinouts for that.
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Looks like it isn't a rail pressure problem then. Sounds like maybe it's a power or ground issue if you put a known good FICM on, and it still sets the U1800 code. I know you installed new fuses, but did you verify that the FICM power fuse is getting hot when you turn the key on?
JoshH, im getting ready to got into the 100* heat today and start back probing the harness and see keyed power supplys. I have a few power leads from the ecu i was able to identify.
2004lb7, I've been trying to find an 03 lb7 ficm pinout but been unsuccessful. Are they the same as the lly you just posted?
2004lb7, I've been trying to find an 03 lb7 ficm pinout but been unsuccessful. Are they the same as the lly you just posted?
Was there any kind of kill switch or alarm associated with the auto start? Unfortunately I don’t remember which pin I tapped into for a kill switch but those are the 2 codes I get when I forget said switch. Truck will crank but no start.
No not that I saw. I do have a couple wire open under the steering wheel but they looked to have been added or tapped into for the auto starter. Maybe I need to go back to that set of wires first. Didn't think about that until you just said that darkness. Do you happen to have a diagram for the wires under column or a picture at all? Maybe I have 2 that I need to tie back together to get it to work. This is what was left after taking that out! Didn't find on of those hood open switches either. The PO didn't mention anything about one and he owned it for about 3 years with the autostarter I believe. I have 6 left open connections with the crimp taps. From the diagrams that I was able to find I don't think any are supposed to be tied together?
I don't hear or feel the EDU relay kicking on with the key either. Swapped it with a know working park lamps unit to make sure. Got battery voltage power at the relay terminals 87/85, regardless off key position. Don't have a pin out diagram for the ficm not sure which connector is what to try and pin. My connectors do not have any sort of identification of what pin is what I've seen like A1-A12 on connectors before but not seeing that on these. Any on by chance have an end view pinout diagram?
I don't hear or feel the EDU relay kicking on with the key either. Swapped it with a know working park lamps unit to make sure. Got battery voltage power at the relay terminals 87/85, regardless off key position. Don't have a pin out diagram for the ficm not sure which connector is what to try and pin. My connectors do not have any sort of identification of what pin is what I've seen like A1-A12 on connectors before but not seeing that on these. Any on by chance have an end view pinout diagram?
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You can get the rest here: https://www.gmupfitter.com/wp-content/uploads/2021/05/2005_LD_CKFullSizeElectrical.pdf
This one is the power (pink) to the FICM (EDU)
This one is the power (pink) to the FICM (EDU)
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I want to thank yall for the help today especially the diagrams as i couldnt find any with pinout eariler. I was able to get some more data. So what I came up with when back probing the ECU (with multi meter set on voltage and ground continuity to negative terminal) Please let me know if I am misleading my self as I'm new to electronics on these.
Ecu C1 Blue:
Pin 44 Pnk/Blk Ignition voltage- got nothing.
Pin 79 Gry/Blk FICM relay control - got nothing.
Ecu C2 Clear:
Pin 9 Dk grn/Wht fuel pump primary relay - got nothing.
Pin 42 Ppl/wht FPR supply voltage - got nothing.
Pin 58 Yel FRP sensor signal - got .5v
Pin 77 Yel FPR Solenoid control - got nothing.
All grounds on both connectors have continuity with negative terminal on the battery. All other battery voltage pins or reference pins other that what I stated had 11.3v to 12.3v in run/crank positions as well. I can't see any other spot on the ecu I need to check. Unless yall think I missed one?
I'll hopefully be getting back out there tomorrow to try and figure this out more. Looks like i may be missing some ignition voltage to the ecu for this so ill have to check those wires under the wheel. Anyone have any insight on which wires i may be looking for? Would I be able to take 12v+ and tapping into the gry/blk wire to see if I can get comms at the ficm or is that a bad idea? Thanks again for any input!!
Ecu C1 Blue:
Pin 44 Pnk/Blk Ignition voltage- got nothing.
Pin 79 Gry/Blk FICM relay control - got nothing.
Ecu C2 Clear:
Pin 9 Dk grn/Wht fuel pump primary relay - got nothing.
Pin 42 Ppl/wht FPR supply voltage - got nothing.
Pin 58 Yel FRP sensor signal - got .5v
Pin 77 Yel FPR Solenoid control - got nothing.
All grounds on both connectors have continuity with negative terminal on the battery. All other battery voltage pins or reference pins other that what I stated had 11.3v to 12.3v in run/crank positions as well. I can't see any other spot on the ecu I need to check. Unless yall think I missed one?
I'll hopefully be getting back out there tomorrow to try and figure this out more. Looks like i may be missing some ignition voltage to the ecu for this so ill have to check those wires under the wheel. Anyone have any insight on which wires i may be looking for? Would I be able to take 12v+ and tapping into the gry/blk wire to see if I can get comms at the ficm or is that a bad idea? Thanks again for any input!!
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Yeah battery voltage was lower. Didn't have a battery charger on her today. I will reconfirm those numbers in the morning as the truck sits beside the how and my wife is asleep for work in the am. And it's on a charger overnight. All were tested in the run position minus the crank I tried to read it in the darkness from the cab before it got to late. I'll reconfirm on the connectors in.the.morning as well I had to use the first 2 connectors for my lb7 as the other pcm connections don't match. Blue/clear on my ecu and red/gray on my tcm. Looked though the diagrams to match my connectors. If I use the PCM wiring then my color connectors are incorrect and I'm missing wires so that's why I went with the ecu wires. Or am I missing something here?
