Ignition does not shut off truck after EBL Flash II install

[JDGMC]

I believe it’s plug and play setup for the TBI harness.

 

[Wolvrine82]

Thank you all for your replies. I ordered an additional ecm from rock auto a 1227747 as installed in the truck when I purchased it and sent that for the EBL conversion. The truck starts and shuts off normally with the * "original" ecm installed. As far as the accessories, the oil pressure gauge still works, but the radio powers down. No wiring has been touched. I have an aftermarket stereo to install but wanted to get the truck running properly before doing so. I did check on the calpack id - AKWA - and located the bcc which shows the ecm should be a 1228747 as noted in PlayingwithTBI's reply. I don't know if using a 7747 ecm for the Flash II conversion would cause this issue or not. The truck has been operational since I purchased it in June, but I was getting a code 51 with a constant fast flashing ses. That was the reason for purchasing the replacement ecm from rock auto - which didn't correct the issue. Thus I ordered the EBL Flash II ecm. I, also, could not read any data with the stock ecm's installed but I now receive data on the What's up display app. Sorry, this is kind of rambling.
Immediately prior to installing the Flash II ecm we were running the truck on the stock ecm and it started and shut down normally. I will try removing the fuse tomorrow after work and note which if any accessories stay powered up.

Edit -* "original as purchased ecm"

 

[Wolvrine82]

Yeah, I saw your post over there. You may wanna try here, he usually haunts this site. HTH

www.thirdgen.org/forums/diy-prom/356351-tuning-ebl-105.html?ispreloading=1

Thank you.

 

[GrimsterGMC]

Just as a side thought, when you added the 3 wires to your harness for the cable to connect up to a laptop, did you double check they went into correct positions? I can't say that would cause this problem, but if it is the only change made besides the ECU it could have an effect.

 

[Scooterwrench]

These ECM's have a power shut down delay to allow the IAC to reset to start position. Normally it's only a few seconds,maybe as much as ten but is programmable when burning a chip. It shouldn't affect ignition,fuel pump or fuel injectors but you never know what gets crossed up when you are working with an ECM that has been into twice.

 

[JDGMC]

Thank you all for your replies. I ordered an additional ecm from rock auto a 1227747 as installed in the truck when I purchased it and sent that for the EBL conversion. The truck starts and shuts off normally with the * "original" ecm installed. As far as the accessories, the oil pressure gauge still works, but the radio powers down. No wiring has been touched. I have an aftermarket stereo to install but wanted to get the truck running properly before doing so. I did check on the calpack id - AKWA - and located the bcc which shows the ecm should be a 1228747 as noted in PlayingwithTBI's reply. I don't know if using a 7747 ecm for the Flash II conversion would cause this issue or not. The truck has been operational since I purchased it in June, but I was getting a code 51 with a constant fast flashing ses. That was the reason for purchasing the replacement ecm from rock auto - which didn't correct the issue. Thus I ordered the EBL Flash II ecm. I, also, could not read any data with the stock ecm's installed but I now receive data on the What's up display app. Sorry, this is kind of rambling.
Immediately prior to installing the Flash II ecm we were running the truck on the stock ecm and it started and shut down normally. I will try removing the fuse tomorrow after work and note which if any accessories stay powered up.

Edit -* "original as purchased ecm"

The code 51 is an eprom diag code. Which makes sense if akwa was installed on the 127747 ecm. Is there any chance the th400 is not the stock trans? Did the previous owner change the chip to accommodate the th400 and not change the ecm?

 

[PlayingWithTBI]

In other words, the diagram above can visually mislead a little, making it look like
the ECM has 2 sources of operational power. But the reality is that the ignition
switch (via the 10A ECM/IGN fuse) is how the driver communicates to the ECM
whether to run or not.

Yes, to a certain extent but, the ECM always has hot feeds going to it on pins C16, C1, and B1. FWIU, you can't run a .bin from a 1228747 in a 1227747 - hence the code 51 flashing. You probably have been running in "Limp Mode" all this time.

You must be registered for see images attach

Maybe @PlayingWithTBI knows the answer to my question along the lines of what I quoted above.

Any pins need moved to install the EBL as compared to OE ecm?

IIRC, the 1227747 is plug and play but, I'm not sure about the 1228747.

You need to ask BobR (or RBob depending on what site you're on) if your 1227747 modified ECM is interchangable with a 1228747. Then fix the code 51.

 

[Road Trip]

Yes, to a certain extent but, the ECM always has hot feeds going to it on pins C16, C1, and B1.

Yeah, I was thinking about listing all the individual power feeds, but was afraid that it would dilute my point.
But I sure would like to see how the various power inputs are either compartmentalized or shared inside
our computers.

One of my biggest disappointments to date is that I had yet to discover any schematics for the GMT400-era
ECM/PCM/VCM/0411 computers. In a previous life I was classically trained to use large format schematics
(and machine code listings on microfiche) when troubleshooting computer systems, so having to just rely
solely upon what's documented in the FSMs feels a lot like shaking wrapped gifts under the Christmas tree
and trying to figure out what's inside. :-(

IIRC, the 122747 is plug and play but, I'm not sure about the 1228747.

You need to ask BobR (or RBob depending on what site you're on) if your 1227747 modified ECM is interchangable with a 1228747. Then fix the code 51

Great stuff. This is the kind of thing that I really want to get familiar with. Really appreciate you
sharing your experience/expertise in this area.

Looking forward to seeing what the final solution is. Fingers crossed that this thread doesn't
dead end prior this being figured out. :0)

 

[JDGMC]

Yes, to a certain extent but, the ECM always has hot feeds going to it on pins C16, C1, and B1. FWIU, you can't run a .bin from a 1228747 in a 1227747 - hence the code 51 flashing. You probably have been running in "Limp Mode" all this time.

You must be registered for see images attach

IIRC, the 1227747 is plug and play but, I'm not sure about the 1228747.

You need to ask BobR (or RBob depending on what site you're on) if your 1227747 modified ECM is interchangable with a 1228747. Then fix the code 51.

It’s interchangeable regarding the harness. Not interchangeable with regard to the mask as is. For example different VE table, fewer switches, no KS, etc. on the 7848. Assuming RBob was aware of the mismatch he could disable the KS, but would also need to edit the mask (ecm def file) to account for location differences. Not ideal.

 

[Wolvrine82]

Update on the EBL Flash ecm. I went out and started the truck like normal. Switched the ignition off and removed the key with the engine still happily running. I checked the radio - not powered up, checked the heater controls - not powered up, switched on the left turn signal - it blinked twice and the truck died. I initially thought it was because of the low idle. Restarted the truck and switched off the ignition and the truck shut off normally. I've started it probably twenty times since with normal operation of the ignition switch.
I swung by our local salvage yard and they had a 1228747 ecm. I swapped my prom and calpack over and installed it into the truck. Truck starts and runs normally - well normally for it (the idle has been messed with and it has a miss going on) with no ses light. Swapped the EBL ecm back in and still starting and shutting down normally.
I did not get a chance to check for power at the EBL ignition pin or pull the ignition fuse prior to it fixing itself with the turn signal application. So, for now, I will continue on with the EBL ecm and update this thread with any future occurences. Thank you everyone for your kind assistance.