TUNE FOR TOW­ING

Diesel Power - - Top Tech Questions - Raphael Ro­jos via email

QUES­TION: My truck is a four-wheel-drive ’15 Ram 2500. Can the ECM be re­pro­grammed with the same set­tings as the 3500 for more tow­ing ca­pac­ity, since they have the same 6.7L Cum­mins en­gine and 68RFE au­to­matic trans­mis­sion? I asked my lo­cal Ram dealer about do­ing just that, and they didn’t have an an­swer. AN­SWER: Noth­ing you do to a pickup will in­crease its haul­ing or tow­ing ca­pac­i­ties, be­cause they are set in stone by the man­u­fac­turer— like the VIN. You can add a pro­gram­mer, helper springs, big­ger sway bars and shocks, and a huskier hitch or even change axle ra­tios. It may help im­prove han­dling and power, but the bot­tom line from a le­gal (read “li­a­bil­ity”) stand­point is the man­u­fac­turer’s rat­ing re­mains un­changed for that en­gine, trans­mis­sion, and axle ra­tio as it came from the fac­tory. Tow­ing above that limit places all li­a­bil­ity on the driver of the ve­hi­cle should it be in­volved in an ac­ci­dent. In ad­di­tion, if it is still un­der war­ranty, what­ever com­po­nents have been changed/mod­i­fied will be voided. Tow­ing “heavy” can also re­sult in fines if a weigh mas­ter or DOT en­force­ment of­fi­cer wants to be a stick­ler on the topic. The rea­son the ve­hi­cle man­u­fac­tur­ers place cargo/ tow­ing lim­its on their ve­hi­cles is be­cause they have de­ter­mined—through ex­ten­sive on-road and track test­ing in ac­cor­dance With meet­ing a regime of re­quire­ments in SAE stan­dard J2807—that’s the max­i­mum safe level that par­tic­u­lar truck’s cool­ing, brak­ing, steer­ing, sus­pen­sion, axles, and driv­e­train can han­dle. Part of the J2807 test­ing in­cludes ac­ci­dent avoid­ance ma­neu­vers.

Fur­ther­more, re­pro­gram­ming the ECU will have lit­tle ef­fect on tow­ing ca­pac­ity in the first place, as your truck’s en­gine and trans­mis­sion are al­ready tuned the same as they would be in an equiv­a­lent Ram 3500.

Even though Ram 2500/3500HDs may share the same run­ning gear, they have dif­fer­ent trailer-tow­ing lim­its based on meet­ing SAE J2807 test­ing re­quire­ments. Con­trary to some be­liefs, flash­ing a 2500’s ECM with the same cal­i­bra­tion as a Ram 3500 or in­stalling heav­ier springs, hitch, brakes, and other com­po­nents, will not change the fac­tory tow rat­ings for that make or model truck.

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