tow/haul mode?

Well so far I have all of the bugs out of my swap except for tow/haul mode. I have went back in and hooked in a BCM and still am not getting tow/haul mode. I verified with a TECH II that the BCM is seeing the tow/haul request from the switch, but it still is not sending the message. I have also noticed that the cluster is VERY slow to display data from the class 2 data bus, and I have no gear display. To those that have done this swap and have tow/haul working, what BCM did you use? What VIN number did you have programmed in if it is different from your donors? I'm beggining to think my problem is the fact that my BCM is looking for too many modules that are no longer present on the data bus. My donor had pretty much every option available right down to memery seats, ONSTAR and NAV. When I scanned the BCM with the TECH II it actuallu gave me a warning about ONSTAR and NAV not communicating. I'm at my wits end and another couple miles beyond right now with this. I know tow/haul isn't required as the swap works fine without it, but it sure would be nice when towing to help keep tranny temps in check.

I'm pretty sure now I need to find a BCM out of an 01 work truck with no options other than automatic tranny. After unhooking the BCM my cluster works great and all data is displayed rapidly now as well as the gear display works now as well. It must be my BCM is looking for all of the missing modules and is overworking the class 2 data bus and jamming it.

I used a salvage BCM that was removed from a gas 1500 series Suburban. My T/H switch works normally. The BCM used in my conversion was not reprogrammed, even though the GM service manuals sorta suggest they are programmed for a specific application. It works fine.... ;)

Jim

I know my donors sure doesn't work. I guess it has something to do with the ONSTAR/NAV system as when I scanned it with the TECH II it gave me a warning about it not seeing the ONSTAR/NAV system on the bus.

I sure feel like an idiot right now. To put it simple I got it to work, the bad part is the reason it wouldn't work before was my fault. I took it in this afternoon and tried to flash it to a work truck CALIBRATION in the BCM. It said the flash went through, but the BCM didn't take it. I got to digging and found that it showed no voltage at the BCM for IGNITION 3 voltage. Came home and dug into it and found that I had hooked up the IGNITION 3 voltage to the wrong spot in the C1 plug. Swapped it around and the tow/haul light popped on and the cluster works great now. Now I have to go in and finalize the install of the BCM and rig up an indicator light since I'm still using my 95 cluster in the actual truck.

I am so jealous of you guys with the GMT400's with the Duramaxs in them.
I love seeing this stuff. Ordered my conversion book, cant wait. Have my 05 GMC 2500HD Duramax up for sale and constantly looking for a 97-99 Big block Suburban.:)

There are a couple Subs for sale in our classified ad page.
http://www.thedieselpage.com/classad.htm

Jim