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6.7 with tow/haul not working

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9.1K views 11 replies 5 participants last post by  TransEngineer  
#1 ·
i went and test drove a 2007 mega cab with the 6.7 and the tow/haul button did not work nor did the manual shift. the light on the dash did not work for them either. the check engine light was on and that was because someone had put a dual exhaust on the truck and did not reprogram it i think.

i had looked at the fuses but it didnt seem that any had blown for the tow/haul. what do you guys think it could be? i drove the truck and it shifted fine.
on a side note it was showing 14.3mpg on the overhead. the used car dealer also had the dpf and factory exhaust with the truck.
 
#2 ·
I posted in your other thread.
Now seeing this thread, I have but one piece of advice.
WALK AWAY!
A used dealer selling you a truck with all those issues means nothing but trouble.
Used salesman = Politician = Liars. Lips are moving then lying.
 
#3 ·
yea your probably right! the used salesman didnt know crap about the truck! i will probably not buy it, i am just curious to see if it could be a "cheap and easy fix" and if so i was going to use the problems as a bargaining tool!

give the dealers some of their own medicine!
 
#5 ·
if thats the case the dealer should fix it before it hits the lot ready for a test drive, stupid dealer.
 
#7 ·
i am looking for a driver, my current dodge is a work truck and stays hooked up to the gooseneck most of the time. i am wanting a truck to drive. it will mostly be a weekend truck. i want to lift it 8 inches, run some 36-38 inch tires and just drive it. i would like some diesel performance to go along with it. it will not be used off road, but we do get some snow and it will get driven a lot then. no towing, my dually does that. also would be a truck to take the family on vacation and such.

on a side note, the used car dealer said they would fix it and make the truck right before i bought it if i was interested. i did have an oasis report ran on the truck( didnt tell the used car dealer) and it came back clean with the ecm recall done and a really good service record. looks like the oil was changed EVERY 5000 miles. it came from texas to a wholesale lot in pa.
 
#10 ·
The warranty history on this truck is clean - there are NO warranty claims for any engine, trans, drivetrain, or any other repairs. There are only four (4) claims, and those are all for safety or emissions recall actions. One was Emissions Recall G30 (replace oxygen sensor module and reflash ECM), one was Safety Recall H34 (for a dash silencer pad support bracket), and the final two were both for Safety Recall H46 (Inspection, but I don't know for what).

Looks like the original owner still owned it at its last safety inspection (at 109,718 miles, in Sept 2009).

So I see nothing in the warranty history that would scare me away.....
 
#11 ·
thanks, thats pretty much what my guy said that ran the oasis report. i havent seen it just talked to him on the phone. i am going to see what i can figure out about the trans tow/haul not working. what would be the easiest thing to check first? the truck now has 141k miles, but it is very clean and appears to have been well taken care of. i just want to get my ducks in a row before i make an offer on the truck.

thanks for all your help!:thumbsup:
 
#12 ·
Easiest thing, I think, would be to check the resistance of the switch. This switch uses a single sensing wire, plus a ground wire. The resistance (from the sense wire to ground) changes depending on which button is pressed (Tow/Haul, ERS+, ERS-, or nothing). If you check it with an ohmmeter, you should see the resistance change as you press each button.

The switch connects to a 6-pin, natural color connector, which I presume is inside the steering column. The switch is between pins 5 and 6 on this connector. If you look into the connector (on the harness) with the latch up, pins 1 and 2 are on the top, and pins 3-6 are the bottom row. Pin 6 is the rightmost pin on the bottom row. Pin 5 is next to it.

You can also check it at the other end of the harness, which is at the TCM. The TCM is located on the firewall, on the passenger side. It has four (4) electrical connectors on the module, but there will be only TWO harnesses connected to it (the middle two connectors just leak electrons onto the ground :hehe:). You want the bottom harness. The Tow/Haul-ERS switch goes between pins 19 and 20 on that connector (pin 5 at the switch goes to pin 20, and pin 6 goes to pin 19). Looking into the harness side, with the latch up, the top row of pins is 1-10 (from RIGHT to LEFT). The next row is 11-19, etc. So you'll want to check resistance between the left-most pin in the second row, and the right-most pin in the 3rd row.

With no switch pressed, the resistance should be 18,680 ohms. When the Tow/Haul button is pressed, the resistance should be 4,110 ohms. When ERS+ (upshift) is pressed, it should be 1,650 ohms, and when ERS- (downshift) is pressed, it should be 460 ohms.

You should also check the switch sense wire (pin 20 at the TCM, pin 5 at the switch) to make sure it isn't shorted to ground somewhere. Disconnect both ends of the harness (TCM and switch) and check for infinite resistance to a ground (like the engine block).

Your dealer can also check the switch voltage (as read by the TCM) using a scan tool. Tell them to reference the diagnostics for fault code P0957 to see what the voltage readings should be. Hope this helps....