Re: Trailer Brake and Aux Power question
1) The Trailer Power pin that is always live in the hitch plug is the one on the upper right (1:30 o'clock) standing at the rear of the car and looking into the plug (pin E, see below)
2) I’m probably not smart enough to say that the BCM isn’t the problem, but I am having trouble believing it. The wiring diagrams clearly show BCM interfaces and there are none from the battery to the fuses or from the fuses to the trailer hitch and BC connector. I tried to attach JPG’s but it apparently this forum website won’t let me. You can get to them on alldatadiy.com if you’ve signed up with them.
In any case, Pwr Dist Schem #1 clearly shows the Battery feeding the TRLR PWR and TRLR BRK fuses with no BCM in between. Pwr Dist schem #9 clearly shows the TRLR PWR fuse directly feeding the trailer hitch plug pin E through connector X442 (behind the right rear wheel) and the TRLR BRK fuse directly feeding the BC through the X209 connector (under the dash), with no BCM in between. This is also shown on the two Trailer schematics (they end in "V92"). These "V92" schematics DO show the BCM interfaces to the Trlr Stop/Turn Signals and the Backup Lamp circuit (and these circuits are working fine, so the BCM is supporting them.)
4) I know that the Tow/Haul button tells the BCM to change the turn signal flash from 3 blinks to 6. Mine is doing that, so the BCM knows the switch is there. It also lights the light on the dash. I haven't been able to get a trailer on the car yet, but it appears from just driving around that the shift points are changing with the tow mode ON. The voltage increase is a bit harder to identify on an analog gauge. I think my BC can give me a digital readout, but haven’t checked it yet. With respect to the "increases the pressure in the transmission" claim, I have seen it denied in other posts on this forum (or maybe the Arcadia one, I can't recall). I am skeptical of it myself. Oil pressure is usually simply a function of oil pump speed and system flow resistance. It seems odd that GM would intentionally reduce oil pressure (and thus flow) with no trailer (i.e., 98% of the time). If anything, I think this “myth” (if it is one) may have originated in some discussion of how the shift points are changed, or how the pressures in the tranny change with the shift different gears and vehicle speeds (i.e., it may simply be a consequence of the new shift points).
5) I know that many people bring up GM not honoring their warranty for installing the V92 yourself. If I had bought a new vehicle, I probably would have been concerned. However, since I saved $6000 by buying a 1 year old, 16,000 mile, car with leather, a sunroof and a DVD, all of which I would never have bought new, I’m quite willing to take the chance. Everything I’ve installed to get the “tow package” is electrical stuff except the oil cooler and hitch. Therefore, the only thing that I would really have any warranty concern about is the transmission, hence adding the oil cooler. I would certainly hope GM built the car well enough with an oil cooler. Thousands of people add them to many different brands of vehicle and have no problems. I also don’t plan to crowd the 5,200 pound limit, as others seem to be doing.
2011 2LT FWD replaced by 2017 2LT AWD