Does anyone know what messages are actually being communicated between the E54, AL5, and FICM? I mean obviously engine speed and some basics like that, but I was just curious if anyone knew if there was actual sensor data on the J1939 bus? I know the J1850 VPW class 2 shares this data through the OBD connector. Just curious if anyone knew if this data was actually on the J1939 as well. Maybe kidturbo knows the answer to this.
LB7 (E54/AL5/FICM) J1939 messages
- Thread starter buick455
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@kidturbo and Ben Tyler would have the most info on this.
I far as we know, there is a message broadcast on the J1939 right after power up stating "all is well" or some such message. I think this gets broadcast every so often. But I can't recall for sure
Then there is the codes. Off the top of my head, injectors codes, bank codes, and FICM performance code
There is a dedicated crank signal line that is run between the ECM and FICM. The FICM receives a replicated crank signal on this
On the J1939, the FICM only talks, never listens
Why do you ask?
Then there is the codes. Off the top of my head, injectors codes, bank codes, and FICM performance code
There is a dedicated crank signal line that is run between the ECM and FICM. The FICM receives a replicated crank signal on this
On the J1939, the FICM only talks, never listens
Why do you ask?
Just kinda curious if we could use the J1939 messaging for installing a digital race display. AEM for example, but there's many more. There's only a few I've found for using J1850 VPW. But not a lot that looks worth a darn. Plus I assume it'd be kinda slow. J1939 would be much faster. BUT, if there's little to no sensor data, all we'd really get is engine speed and some transmission torque requests I assume. If I was running an aftermarket ECU, it wouldn't matter. But running the E54 for now.
I'm pretty sure all the information you want is on that line. If I'm not mistaken, when kidturbo sniffed it, it was basically GMlan or canbus. Same protocols if I remember correctly
Yep
The CANbus network connecting the ECM, TCM, FICM, and GPCM are running on J1939. Most of those messages stick to J1939 standard. IE: Rpm, Temp, Load, Torqe Mgmt control. However all FICM related messages are GM propritary. Mostly diagnostics on ciricuit status sent to the ECM.
And if I'm remembering correctly, it was one way with the FICM not receiving messages. Only broadcasting. The FICM basically ignores everything on the network and only broadcasts when it powers on and when it reports a code/error
Or in other words, there is no messages on the network that are for or pertinent to the FICM
yeah sounds correct. It's always broadcasting, 2 messages. And they may run some FICM diagnostics on top, but we never got around to digging that deep. Basically just a couple rolling counters to show it's alive, and then status of each circuit.