LLY FICM

[2004LB7]

I should be able to back probe the signal wires at the connector. For the current, don't I need an AMP clamp? I believe I have one of the revised Amp Clamps for the lower Voltage. I need to dig it up any way...

As long as your amp clamp can measure DC. Most are only for AC current. Most DVM's require that you put the leads in series with the load to measure the amps. so in your case, if you where to not use an amp clamp, would either have to cut the wires or maybe pull the fuse and stick the meter leads in the fuse slot to measure the current. Voltage drop on the fuse will get you close too

 

[1FastBrick]

I know we argued with Snap on about this and I believe I have revision D which should be ok for DC
Snap On part number EETA308D

 

[2004LB7]

I know we argued with Snap on about this and I believe I have revision D which should be ok for DC
Snap On part number EETA308D

That should work perfectly

 

[1FastBrick]

I found the amp clamp but can't remember where the damn test lead kit is at...

 

[TheBac]

Jason, on the wiring diagrams you posted for that comm issue thread, #52 on the ECM connectors are for the "FICM relay control". Could this be part of the issue with using the LB7 FICM?

 

[2004LB7]

Jason, on the wiring diagrams you posted for that comm issue thread, #52 on the ECM connectors are for the "FICM relay control". Could this be part of the issue with using the LB7 FICM?

That relay only turns on the power to the FICM. The power to the FICM is in the same pin location. So if the ECM wasn't turning on the relay then the FICM wouldn't get power. Regardless of whether it's an LB7 or LLY FICM installed. It would be an easy test to see if there is power at the FICM fuse bit I don't see anything that would keep the ECM from turning on that relay with an LB7 FICM installed

You can see here that the circuit is the same for both. Just the pin in each ECM is in a different location

 

[2004LB7]

Per this thread, the illusive Ben states that the communication for the LB7 and LLY should be exactly the same (excluding the 01-02 for some modules) and all ths modules should be swappable between them and work just fine. Infact this should be true all the way up to 07 1/2. So if the communication is the same then the last thing I can think of is the actual message or what is being said to or received from the FICM that makes the LB7 not work on the LLY

GM module communications explained

***This is a very in depth post completely explaining how the modules in our trucks communicate to one another. It was copied from this thread.*** Well first things first, yo uare dealing with 2 COMPLETELY different data protocols in the truck. The 06 truck uses CAN BUS for the BCM, ECM, and...

www.duramaxdiesels.com

 

[TheBac]

...and you guys chuckled when I said that it could be what was actually being said.

 

[1FastBrick]

Still can't find the pig tail leads for the meter... The Amp Clamp will probably work but It was not stored properly and I forgot about the internal 9V battery... fortunately the connection is not corroded. I tried to see if I could get the cord to the meter replaced but Snap on doesn't offer repair on that item...

Decided FK It... I will just order a new one. I Need to find out if they have a replacement lead kit. Neither the part number for the lead kit or the clamp kit show up.

 

[PureHybrid]

Well 2004LB7 must have some good magic potion, snapped the FICM into the harness real quick. Truck fires up and revs fine, I'll be putting some miles on it too

 

[Chevy1925]

Well 2004LB7 must have some good magic potion, snapped the FICM into the harness real quick. Truck fires up and revs fine, I'll be putting some miles on it too

Jason knows his electronics lol

 

[TheBac]

Well, looks like someone just opened a new business opportunity.....

 

[2004LB7]

That's awesome. I don't imagine everyone will come out working but the fact that the first one did is a good sign that "condemned" ones may no be so hopeless after all.

 

[2004LB7]

Well, looks like someone just opened a new business opportunity.....

Looks like I need to get me an LLY to play around with and test out the repaired ones on

 

[Chevy1925]

If we get more at the shop, jason, I’ll send you some.

 

[board350]

New here, been out of the Duramax scene for a while but got an LLY from my dad. Crank no start situation and found EDU fuse blown and opened the FICM. Found the far right CAP blown. Took them out and cleaned up board as best I could. To test the for shorts I took a wild chance and plugged in FICM and cranked the engine. I just wanted to see if it would still blow the fuse. To my surprise not only did the fuse not blow but the engine fired right up, with no CAPs at all!! I subsequently put two new CAPs in the good spots on the board and left out the blown position. Same result, the engine still runs. I actually drove it today about 25 miles with no issues. I'm not sure if I want to try and put the last CAP back in or just see how long it goes. I'm still in a bit of shock actually. I'd be interested in anyone else's thoughts on this?

 

[board350]

I have a couple videos I will try and load somehow.

 

[board350]

Here's the YouTube links

Source: https://youtu.be/-xTtOqEU85o?si=ICo_HOjbjX7i6jFV

Source: https://youtu.be/geZSV4B3bY0?si=fVL3AJ1pcQFjM4j8

 

[2004LB7]

New here, been out of the Duramax scene for a while but got an LLY from my dad. Crank no start situation and found EDU fuse blown and opened the FICM. Found the far right CAP blown. Took them out and cleaned up board as best I could. To test the for shorts I took a wild chance and plugged in FICM and cranked the engine. I just wanted to see if it would still blow the fuse. To my surprise not only did the fuse not blow but the engine fired right up, with no CAPs at all!! I subsequently put two new CAPs in the good spots on the board and left out the blown position. Same result, the engine still runs. I actually drove it today about 25 miles with no issues. I'm not sure if I want to try and put the last CAP back in or just see how long it goes. I'm still in a bit of shock actually. I'd be interested in anyone else's thoughts on this?

Those capacitors are just the power in smoothing capacitors. Probably not too critical as the Battery probably does more smoothing then the caps woll ever do. But helps with line noise that might make it down the wire as they are run right next to the high voltage injector wires

The larger capacitors are the important ones and it won't run without them

 

[board350]

Well I couldn't leave well enough alone. I put in two of the capacitors and it still ran fine. Then I tried to put in the third one where the board had blew out and it ended up shorting it out and I couldn't fix it. I ended up getting a junkyard FICM and replaced all five capacitors on that one and it's running fine. Thanks for all the help.