Ls Conversion guys, a quick ?

[Big Port Jimmy 6]

Does any one have a tow/haul mode without using the BCM? Apparently the BCM communicates with the PCM by serial data to make the mode in the trans change. Thanks Jay

[Cherub]

not familiar with the term bcm.

[Gemp]

Body control module

[78-5.3]

what year did they install them ive never heard of 1 my is a 2002

[silvereagle07]

Ive seen that option in the tow package in a 99 01 and 06 that my family has. Its the switch on the end of the shift lever.

[Big Port Jimmy 6]

The BCM is the computer that controls "body" functions. It controls the dash display, the power windows, the AC actuators, all of the courtesy lights, power locks and keyless entry. It also sends out all of the tones like the seat belt buzzer lights on buzzer etc, it interfaces with the radio to do this and is probably the hub for the steering wheel radio controls.I am sure to have forgotten any number of additional functions. It communicates with the PCM by serial data on pin 58. If I could mimic the signal I could switch the trans modes. BCMs have been in GMs since the 90s and like the PCM have grown much more complicated. I originally was going to try to integrate a BCM to my 87, mainly for the factory keyless entry and the theater lighting, but it got fairly complicated real fast and in a hurry. Jay

[87chevy.com]

nah, I wish they did, the LS1 computers uses a momentary ground... how convienent... Ive been hovering on HPtuners and no one has gotten it to work. I read that some guy was engeneering a pc board to get it to work, or he made one for himself. I think anoher peron tried to hook up just the bare necessities, power ground and the tow haul control and it didnt work. dont know why, but thats what i remember about that post. I wish there was something out there (cheap) that allowed us to run that feature.
clint

[87chevy.com]

Anyone a GM electican tech??
it seems that you have to program this module if you replace it...
would a junkyard one need to be programmed?
and if it needed programming, could you program such a module to match a engine and trans wiring combo only?

im not a gm tech, but i use to work at a chevy dealer so maybe the same electrician tech still works there and remembers me.. if so I might have to leave work and talk to him in person with a case of beer in one hand and a note pad in the other. From the transmission schematic, it looks as if the tow haul is just a momentary contact between ground and a pin on the bcm, and then the bcm makes its signal to the PCM. sounds easy enough but I swear I read someone had tried to wire the BCM up like I just described and it didnt work.
If anyone has any BMW questions, Im your man GM BCM's not so much..
thanks

[Big Port Jimmy 6]

I don't think its just a ground to the pcm. The pcm gets serial data on pin 59. Serial data from the bcm, I am not sure which other functions the bcm would turn on or off in the pcm? I used to be a GM tech and still have pretty food access to technical data.

[Gemp]

Someone might know more over on LS1 Truck.....

http://www.ls1truck.com/forums/

[clinebarger]

Originally Posted by Big Port Jimmy 6

Does any one have a tow/haul mode without using the BCM? Apparently the BCM communicates with the PCM by serial data to make the mode in the trans change. Thanks Jay

I tried for 2 months. What i learned is flashing the anti-theft out of the PCM makes the PCM ignore what input it gets from the BCM. Maybe you can use a PCM that doesnt have the anti-theft removed the have the anti-theft/passlock turned off in the BCM? The PCM & BCM will need the same VIN flashed into them.

Originally Posted by Big Port Jimmy 6

It communicates with the PCM by serial data on pin 58. If I could mimic the signal I could switch the trans modes.

Pin 58 is a dianostic/flash serial data line shared by all modules. The BCM uses pin 59 (right next to pin 58) to communicate with the with the PCM.

[87chevy.com]

thats the same schematic i seen in alldata. after reading some neat information about class2 j1850 vpw, it seems like power, ground to the module +
PCM C1 pin58 wired into BCM C1 pin a12
momentary swtich going from chassis ground to BCM C1 pin B12
BCM C2 pin A1 to PCM C1 pin 59
It should work if its programed. Thats what im unsure of. Since your PCM has a VIN number, I wonder if you could take the dealership a USED BCM and have them reflash it with your VIN number, but hooked up to a customers or stock truck and work? I also need to see if i can find a pinout of all wires of the BCM to find out what the other inputs are. If i had to guess, the inputs are all momentary grounds, but i would want to look at the schematics anyway.
Taking a lsx truck to the dealer and having to explain to the advisor, hey I want you to program my BCM would be like telling an ape how to use tolite paper. Hopefully I can have some ducks in a row before I go bug the GM electrician..
clint

edit:
i wonder if HPtuners has a VCM control for tow/haul. if so, I want to activate it and see if the truck responds accordingly. It seems wierd how deleting the security thing from the pcm affects what it seens from the BCM...

[Big Port Jimmy 6]

Clinebarger you are right with the pin numbers. I was flying by memory and it just aint what it used to be. I will look into integrating a bcm after I finish the swap. I will probably source up one from the salvage and try to flash it the vin of the truck that the 5.3 came from.

[87chevy.com]

so can you flash the bcm with the power, ground, and both class 2 wires hooked up?

[87chevy.com]

so alldata doesnt have a complete pinout diagram of the BCM but it did give a power,ground and class2 diagram, when combined with the above schematic, I merged the 2 in MSPaint (see attachment). Man, althought I probally wont use the tow/haul option much... now that Ive invested all this brain work, I want to see if I can get it to work aswell. I wonder what it would take to program this sucker. I mean would the module fail if it cannot talk to the other modules that arnt connected. I work at BMW and modules fail on occasion while programming and it doesnt disable the car, that one module just doesnt work. We no longer have the option to program one module of our choosing, but it completly updates the car. GM is probally different.

clint

[87chevy.com]

I started my original post created on 09/2008 on hptuners and it looks like the 0411 PCMs were used in vetts, ls1s and so on... so their mod was to change a calibration in the transmission table (i will take a look at the options tonight and post a screenshot if i can find it) and wire the momentary ground to pin 71 of the BLUE PCM connector. I still dont know how they figured that out becuase all of the diagrams I have found show pin 71 not used for truck and LS1's... genius I tell ya...
If it does have this option, Im going to be nervious about putting ground to that pin on my own computer. I have a spare 0411 PCM but it still will cost 100$ in HP credits...

clint

edit:
Ive been told it should work, so Saturday or Sunday I am going to give it a whirl... High Hopes

[Big Port Jimmy 6]

Keep us informed. Jay

[clinebarger]

Originally Posted by 87chevy.com

I started my original post created on 09/2008 on hptuners and it looks like the 0411 PCMs were used in vetts, ls1s and so on... so their mod was to change a calibration in the transmission table (i will take a look at the options tonight and post a screenshot if i can find it) and wire the momentary ground to pin 71 of the BLUE PCM connector. I still dont know how they figured that out becuase all of the diagrams I have found show pin 71 not used for truck and LS1's... genius I tell ya...
If it does have this option, Im going to be nervious about putting ground to that pin on my own computer. I have a spare 0411 PCM but it still will cost 100$ in HP credits...

clint

edit:
Ive been told it should work, so Saturday or Sunday I am going to give it a whirl... High Hopes

Can you give a direct link to your thread? I whould like to read it before I give an opinion.

[87chevy.com]

no prob,
http://www.hptuners.com/forum/showthread.php?t=19831
the guys that designed HPtuners is a genius....

[Manbearpig]

EFI Live > HPTuners :P

[clinebarger]

Originally Posted by 87chevy.com

no prob,
http://www.hptuners.com/forum/showthread.php?t=19831
the guys that designed HPtuners is a genius....

Thanks. I read it, He didnt say if hes using a factory "tow/haul" setting? Sounds like a custom Tune with high line pressures? I think tuners get too aggressive with shift timing & line pressure. But they dont warranty a transmission because of it either.

[87chevy.com]

dangit, i hit refresh and lost all of my post..
anyway, yeah to get the feature to work, its a custom tune. To get the swap to work anyway its a custom tune ... I recon some tuners go crazy but my settings feel great. I went with a well known reprutable tuner so I wouldnt have any issues. I only had to tweak the MPG setting on one of the tables... the thing huted for a gear becuase of the speed i was cruisng at.. no biggie at all.
clint

[Big Port Jimmy 6]

Yeah it is a custom tune, had to remove vats and the rear o2s. I had him turn the torque management down. I am going to install a transgo shift kit to take care of the shift firmness. Tow\Haul should be close to stock. Jay

[dan76]

Originally Posted by Gemp

Body control module

I once had a girl friend with one of these....

Seriously though, this is an interesting thread and I'll need the information on a pending 6.0 swap.

[87chevy.com]

Ive installed 2 transgo shift kits for the 4l60e.. pretty strait foward. when you pull the "plunger down" from the pump... if you cant get that sucker, drill a small hole and insert a screw and pull the screw down. the pliers sliped on the nub of the plunger and what part of the transmission my elbow hit, but it left a gash that forever to heal.
I borrowd HPtuners, modified the trans table, going to hook up a temporary ground switch to test it out tomarrow.
clint