Transmission Slip

[Gapper_ca]

Help! i was towing my camper last night and suddenly the Banks PDA gave me an error that it had detected trans slip! it cut out its extra power but truck did not. the trans temp was 180 engine 195. not pulling a hill or anything, power level was on 5 more to go yet. speed was 60 very good conditions. read the slip% and it was 0-4..6 then steady at 1 or 0% . check fluid level and it was ok. any ideas??

[DmaxMaverick]

Too much power for a stock tranny. Especially towing. When you increase your power with a programmer, power is put through the tranny much sooner than the TCM anticipates (less TPS input), and the tranny doesn't downshift like it would under the same conditions at stock power. At least the system you have protected your tranny to some degree.

Upgrade the tranny, decrease your power, or keep your foot out of it. While towing, only the lowest power increases should be used, as also recommended by Banks.

[Gapper_ca]

ok but was not pushing it at all, and truck had no codes. just what upgrades to trans should one do? i pull a 7000lb trailer over flat land, no mountains yet....

[DmaxMaverick]

You'll have to check out Suncoast or ATS (or the various distributors for these) for tranny upgrade options. They vary from expensive to very expensive.

It's hard to say why it happened. More details would be helpful. Speed, weight, acceleration, fuel filter condition, last tranny service (fluid/filter), tire size, fuel quality (#2, winter blend, bio, VO). Rolling into the throttle (with added power) will increase input torque more quickly than the TCM will respond. It is more profound with higher gears. The power increases, with less increase of ground speed, at a lower TPS input. If the tranny is going to slip, this is when it will happen. And, it's not just the tranny. The torque converter also has a limit. All this depends on the gear, speed, throttle input, and how much power is applied.

You didn't get DTC's because the PDA caught it before the TCM did (sounds like a good thing), and pulled power before the slip reached the TCM limit. Had the TCM intervened, you would have been in limp mode, not just a decrease of your Banks power. It's a warning. Take it serious before a tranny upgrade is compulsory.

[Gapper_ca]

well made the trip home today. power level 3 to 6 played with it a bit more but cut out the OD when pulling a incline. seemed to be much better, slip was steady at 1 to 5 % depending on throttle and road. bucking a good cross wind as well. no codes or faults. power % was 0-60% when OD locked out. kept speed close to same , slower at times but over all same as last trip. think it was just the not having OD locked out, according to GM not pulling enough to even use the tow/haul mode. using cruise and a slight incline was enough to set Banks off.

[DmaxMaverick]

Start saving now for your tranny rebuild. Keep towing, even moderate loads, at those power levels, and continue seeing steady slips of 1-5%, and you'll need that rebuild sooner than you think. There will come a time when your tranny won't hold stock power in an empty truck over an overpass. The damage is cumulative. You only get so much before it can't compensate any more.