tow/haul mode?

[THEFERMANATOR]

This is mainly a question for those with completed swaps, but what all did you have to do to get the BCM to command tow/haul mode? I currently have my donors 01 BCM hooked up to the two class 2 data bus's, the guage cluster hooked up to the OBD2 port and still cannot get the tow/haul mode to engage when I ground the tow/haul switch wire. I don't have a tech2(just EFILIVE), but I am assuming the BCM and cluster are working since the 2 temp guages are working in the cluster and they both show up when I do a module scan with EFILIVE.

This is my only hurdle left to get around in my swap, and with my current gearing and useage I really need the 2 different shift patterns to keep the engine and tranny happy(I got some overheating when towing before from it not locking in the TCC).

I tried ALLISON and they said they can't program my TCM since it isn't in a medium duty or larger(EPA won't let them program light duty they said), and DESTROKED's set-up is pretty expensive and would eliminate the can bus in between the ECM and TCM. I could probably wire in an XFC which is what they use in there set-up to make tow/haul work and to provide the TPS signal, but $500 for a box just for tow/haul seems like a bit much. Sorry for the long winded post, but I am at my wits end here trying to get this to work.

 

[SmokeShow]

I have no idea but have you spoken with PPE? How about Brayden?

 

[THEFERMANATOR]

PPE said I could have one or the other, and BRAYDEN tried but couldn't get tow/haul to work on a toggle. I'm going to see if I can use a tech @ in the next day or 2 as I see I have some other problems with my new to me TCM. I had a HORRIBLE time flashing it to begin with as it kept poping up as invalid calibration, then I had to flash it without high speed which took 32 minutes to flash in. It drives fine after it did it's first 3 shifts and all seems to work as far as the tranny goes, but it won't display gear position and will only display trans temp intermittently on my donors cluster. I know the TCM is active on the bus as I can scan it with EFILIVE and just flashed it yesterday.

 

[PANCHORFO]

good to know how to engage the tow/haul mode in a duramax swap

 

[THEFERMANATOR]

good to know how to engage the tow/haul mode in a duramax swap

Once I get it to work(if I can) I will post it. The only real option I have found though is an 06 VAN BCM, but I'm still not certain it will work on my 01.

 

[SmokeShow]

Previously you said you can have one or the other... one is T/H, what's the other thing you have to do without if you have T/H?


C-ya

 

[THEFERMANATOR]

Previously you said you can have one or the other... one is T/H, what's the other thing you have to do without if you have T/H?


C-ya

Like it is now I could program it with a KODIAK tune which would be locked in tow/haul mode and I would lose my OD/LO, or run the 02 I'm running now and have normal shift mode with an OD/LO. I need to run up to radioshack and pick up a few pieces and see if I can get the BCM to work. I also found a VIN number that I may have to have my BCM flashed to in order to work as my BCM is looking for ALOT of modules that aren't there(ONSTAR, TCCM, NAV, and so on).

 

[duratothemax]

do you have ALL of the batt, ign, ground, and class 2 wires hooked up to the BCM? There are about 3 or 4 of each. Also, the two tow/haul switch wires from the BCM need to be touched together...if you just touch one of them to ground it will not work as far as I know.

is there anyone close by with a tech 2 so you can read out BCM data?

Ben

 

[THEFERMANATOR]

do you have ALL of the batt, ign, ground, and class 2 wires hooked up to the BCM? There are about 3 or 4 of each. Also, the two tow/haul switch wires from the BCM need to be touched together...if you just touch one of them to ground it will not work as far as I know.

is there anyone close by with a tech 2 so you can read out BCM data?

Ben

Theres 2 grounds, a battery power, IGNITION 1, and IGNITION 3 that are all hooked up on it. The tow/haul switch grounds directly to the chassis on an 01 according to my ALLDATA diagrams, but they have been wrong before. I have both of the class 2 data lines connected up, yet still no tow/haul and my cluster isn't always showing data. I believe my problem is the security system is shutting the class 2 data bus down and not allowing the tow/haul message to transmit as I have no passlock sensor in my lock cylinder. I picked up some resistors today and am going to try and put a resistor in and do the passlock learn so that the BCM thinks the engine SHOULD be running and see if that helps. I also got a VIN number for a bare bones 2500HD with manual shift 4X4 that I will probably try and get flashed into it. I know it will work without ABS and airbags being hooked up as Bigleys truck doesn't have those and his works. I can get access to a TECH2, but it is at the local dealer so I can't bring all of my tools with me to do my testing(they won't let me leave the lot with the TECH 2, and there TECH1 isn't updated past 94).

 

[duratothemax]

security will not have an effect on this.

 

[THEFERMANATOR]

security will not have an effect on this.

I guess it's time for plan B(or is it C,D,E,F, or whatever in the hell it may be). Relearning PASSLOCK didn't help a bit, but I figured it was worth a shot. I know the BCM works as I re-enabled the theft system in the ECM and iot wouldn't start, I did the re-learn with the key and it started up fine. What I am noticing is it takes a good 5-8 seconds from the time I start it until any data is displayed via the cluster from the ECM, and the trans temp only reads on initial start-up along with no gear indicator. I went and used a TECH 2 for a few minutes this afternoon and the BCM is seeing the tow/haul request from the switch, but it still doesn't engage the light in the cluster or switch in the TCM data display. When I was in the IPC it showed invalid for the gear display, and the trans temp it showed didn't match that the TCM said it was reading. Also when I accessed the BCM it flashed up a warning message about the ONSTAR/NAV not being present. I wonder if I flash the BCM to a different VIN of a bare bones work truck if that will help. The only thing I can think of is the class 2 data bus is being overloaded by the BCM looking modules that aren't pressent on the bus. My BCM is programmed for just about every option available, but I only have the ECM/TCM/BCM/IPC on the bus right now.

Also, what are the chances that the SDM may be causing this? When I was at the dealer they said they have seen problems when the SDM isn't there or the VIN doesn't match.

 

[THEFERMANATOR]

For the heck of it I unhooked my BCM from the bus and now my cluster works great except for the security light being on all the time. The gear display works now as well as all of the class 2 data bus driven guage signals. I guess I need to find a dealer with some actual techs that know how to set-up a BCM. I know BIGLEYS works fine without all of the other modules on the bus, so I don't see why mine can't. When asked the dealer I normally deal with they told me it would cost $50 just to get GM to send them the info to program my BCM, and even then they said they wouldn't be able to flash my old BCM. It would be nice if I could find a BCM out of an 01 work truck that had an auto.

 

[THEFERMANATOR]

I finally got it to work this afternoon. I went down and tried to flash it to a work truck cal in the BCM with a different VIN, for some reason the MDI said it went through but the flash didn't go through. I started checking the BCM inputs again and found that the IGNITION 3 voltage showed inactive. Came home and found that I had hooked up the IGNITION 3 wire to the wrong terminal in the C1 plug. Swapped it around and tow/haul works fine now.

 

[SmokeShow]

That's awesome man!

 

[duratothemax]

I started checking the BCM inputs again and found that the IGNITION 3 voltage showed inactive. Came home and found that I had hooked up the IGNITION 3 wire to the wrong terminal in the C1 plug. Swapped it around and tow/haul works fine now.

do you have ALL of the batt, ign, ground, and class 2 wires hooked up to the BCM? There are about 3 or 4 of each.

ahhh ha!

glad to hear it works now! So does the cluster need to be hooked up for t/h to engage? Or can you just wire in the BCM and stuff it under the burban's dash and leave the stock dmax cluster unhooked?

 

[THEFERMANATOR]

Tow/h aul mode engages just fine without the DURAMAX cluster in place. You don't have any indicator, but it comes on just fine. Since I have no use for my 01's cluster and preffered my 95 clusters look, I took the 01 cluster apart and removed the circuit board. I took a small dremel with a cut-off wheel and carefully cut the logic module out of the board, and I then took a jumper and hooked in like you would for the co-pilot and hooked the other side up to an unused pin in the plug. I hooked it up under the dash along with the cluster and hooked in 2 momentary switches and 2 led's so I now have OD/LO and tow/haul mode along with working indicators for them. It's a redneck engineering marvel really, but works great. I still don't notice any grade braking when I came down a hill with it, but from what I have found the TCM needs input from the ABS module before it will engage grade braking. It's not a big deal really as having the torque converter locked up and the aggressive downshifts in tow/haul make it stop nicely without a trailer on the back. Just need to tweak the shift points a bit as I have to be running a bit over 65 before I get 5th in tow/haul right now, figure I'll drop it back to 58-60 and call it good.