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Tow/haul Not Working

ss502gmc
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ss502gmc Enthusiast

ss502gmc

Posted
Posted

Today i just noticed on my 01 2500hd that my tow/haul isnt coming on now. Ive never had this happen before and am curious to know if anyone has ever seen this and if so how do i fix it. I dont know the first place to look for something like this. I tried it thinking maybe the bulb burnt but it just doesnt work at all. I fo alot of heavy hauling so id like to fix this asap. Any help would be great!

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tjg79
tjg79

Tow/Haul Switch/Indicator Always On or Inoperative   4L60/4L60-E/4L65-E Transmission     Circuit Description Tow/haul mode enables the operator to achieve enhanced shift performance when tow

gmtech4
gmtech4

Diagnostic Trouble Code ,   Someone should supply descrip and operation , it either changes shift points or adjusts transmission oil pressure to hold clutches stronger   You can purchase Alldata.

gmtech4
gmtech4

yes but its not as obvious like ear;ier yrs where ya can see the 200 rpm jump ....its PWM now and that means its ramped up and ya dont feel it ,,,,   somebody needs to post a description and operati

Posted Images

Hammer2785 Enthusiast

Hammer2785

Posted
Posted (edited)

Have you checked the orange wire in the steering column that runs to the switch. It has a tendency to break and then the switch doesn't work. I fixed mine with a splice connector and some heat shrink tubing.

Edited by Hammer2785
tjg79 Enthusiast

tjg79

Posted
Posted (edited)

Tow/Haul Switch/Indicator Always On or Inoperative

 

4L60/4L60-E/4L65-E Transmission

 

post-39679-1256422081_thumb.png

 

Circuit Description

Tow/haul mode enables the operator to achieve enhanced shift performance when towing or hauling a load. When tow/haul mode is selected, the tow/haul switch input signal to the body control module (BCM) is momentarily toggled to zero volts. This signals the powertrain control module (PCM) to extend the length of time between upshifts and increase transmission line pressure. Cycling the tow/haul switch again disables tow/haul mode and returns the transmission to a normal shift pattern.

 

Diagnostic Aids

If the electrical circuit tests are OK and the tow/haul shift pattern is not occurring, there may be a mechanical/hydraulic condition that prevents tow/haul operation. Refer to Symptoms - Automatic Transmission.

 

post-39679-1256422245_thumb.png

 

post-39679-1256422270_thumb.png

 

Test Description

The numbers below refer to the step numbers on the diagnostic table.

 

2. This step tests for a faulty tow/haul switch.

 

3. This step tests for voltage input from the BCM to the tow/haul switch.

 

6. This step tests for voltage through the body wiring harness junction block.

 

7. This step tests for ground integrity at the splice pack.

 

<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

4L80-E/4L85-E Transmission

 

post-39679-1256433098_thumb.png

 

Circuit Description

Tow/haul mode enables the operator to achieve enhanced shift performance when towing or hauling load. When tow/haul mode is selected, the tow/haul switch input signal to the body control module (BCM) is momentarily toggled to zero volts. This signals the powertrain control module (PCM) to extend the length of time between upshifts and increase transmission line pressure. Cycling the tow/haul switch again disables tow/haul mode and returns the transmission to a normal shift pattern.

 

Diagnostic Aids

If the electrical circuit checks are OK and the tow/haul shift pattern is not occurring, there may be a mechanical/hydraulic condition that prevents tow/haul operation. Refer to Symptoms - Automatic Transmission.

 

post-39679-1256433128_thumb.png

 

post-39679-1256433151_thumb.png

 

Test Description

The numbers below refer to the step numbers on the diagnostic table.

 

 

2. This step tests for a faulty tow/haul switch.

 

3. This step tests for voltage input from the BCM to the tow/haul switch.

 

6. This step tests for voltage through the body wiring harness junction block.

 

7. This step tests for ground integrity at the splice pack.

post-39679-1256422081_thumb.png

post-39679-1256422245_thumb.png

post-39679-1256422270_thumb.png

post-39679-1256433098_thumb.png

post-39679-1256433128_thumb.png

post-39679-1256433151_thumb.png

post-39679-1256422081_thumb.png

post-39679-1256422245_thumb.png

post-39679-1256422270_thumb.png

post-39679-1256433098_thumb.png

post-39679-1256433128_thumb.png

post-39679-1256433151_thumb.png

post-39679-1256422081_thumb.png

post-39679-1256422245_thumb.png

post-39679-1256422270_thumb.png

post-39679-1256433098_thumb.png

post-39679-1256433128_thumb.png

post-39679-1256433151_thumb.png

Edited by tjg79
  • Like 2
  • 2 years later...
Nichevo Enthusiast

Nichevo

Posted
Posted

This is great. Could anyone please supply relevant part numbers?

tbhuge Enthusiast

tbhuge

Posted
Posted

Same thing happened to me a few months back. It was the wires coming out of the shifter. If you take the covers off your steering column, it is plain as day which wires we are talking about. Mine was a very obvious break. The wires for this area should have a lot more protection around this area. GM flaw..... If you follow the wires on down it as its own connector. Take the connector apart and one bolt and you can put the entire assembly on your workbench to resolder or fix it. If I were to rate the difficulty of this, I would put it in the beginner category. I had more of a challenge trying to figure out how the covers unsnapped from each other than anything else.

  • 1 year later...
dhoyoss New Member

dhoyoss

Posted
Posted

Tow/Haul not turning on. Pryed steering column covers apart just enough to see the two small white cables wrapped in a orange sleeve cut in half like Hammer2785 said. I also spliced the two wires and wrapped in electrical tape. Tow/Haul now works!!!

Kalabin Enthusiast

Kalabin

Posted
Posted

I ran into this about two months ago, I spliced the wiring myself but being that it's stranded and like 26awg the splice didn't last. A brand new shifter with the tow/haul mode etc cost a whole 60 bucks. Just removed the old shifter and popped the new on in place. Figure for the cost of an oil change i'll mark it up to maintenance.

  • 4 months later...
ziffel Enthusiast

ziffel

Posted
Posted

I thought there were some "gifs" posted with this topic. I don't see them now. I'm having trouble with my 09 tow haul and that info may help. Thanks Ziffel

00Silverado4x4 Senior Enthusiast

00Silverado4x4

Posted
Posted (edited)

If the steering column wires are the problem; it also could be your brake pedal switch as well. They have been known to give out from time to time.

 

Totally disregard this post, I was thinking cruise control...brake light switch and tow/haul have nothing to do with each other...my apologies.

Edited by 06SierraZ71
Pulled my head...
ziffel Enthusiast

ziffel

Posted
Posted

Not the steering column switch or harness. Check them visibly and with continuity light. Tell me more about the brake pedal switch. Is it part of the stop light switch or a separate device? When I push on the tow haul button the indicator on the cluster is on but it has no effect on the transmission. Loaded or unloaded at any speed. It hasn't worked since I got the truck. The dealer said it is just fine. Quote .."It is operating within the parameters set by GM for that truck that year" I have driven other 09 Silverado's and they work just fine. Mine is a 1500 WT 4.8. Did GM tamper with them in an effort to raise fleet mileage numbers or for some other reason. If so what can be done? I bought this truck to tow an RV so the tow haul is important. Thanks..Ziffel

gmtech4 Senior Enthusiast

gmtech4

Posted
Posted (edited)

Not the steering column switch or harness. Check them visibly and with continuity light. Tell me more about the brake pedal switch. Is it part of the stop light switch or a separate device? When I push on the tow haul button the indicator on the cluster is on but it has no effect on the transmission. Loaded or unloaded at any speed. It hasn't worked since I got the truck. The dealer said it is just fine. Quote .."It is operating within the parameters set by GM for that truck that year" I have driven other 09 Silverado's and they work just fine. Mine is a 1500 WT 4.8. Did GM tamper with them in an effort to raise fleet mileage numbers or for some other reason. If so what can be done? I bought this truck to tow an RV so the tow haul is important. Thanks..Ziffel

Don't start with a conspiracy theory , if the tow haul doesn't work then there is a DTC ,, it may be a pressure change , if some one can get a description and operation for him and post it , that would be great,

 

The reason I ask is I don't have access on my tablet on vaca , I don't want to guess as to the programming change during the tow/haul operation

Edited by govtech4
gmtech4 Senior Enthusiast

gmtech4

Posted
Posted

Diagnostic Trouble Code ,

 

Someone should supply descrip and operation , it either changes shift points or adjusts transmission oil pressure to hold clutches stronger

 

You can purchase Alldata.com for $27/yr

  • Like 1
02suburbanZ71 Senior Enthusiast

02suburbanZ71

Posted
Posted

Diagnostic Trouble Code ,

 

Someone should supply descrip and operation , it either changes shift points or adjusts transmission oil pressure to hold clutches stronger

 

You can purchase Alldata.com for $27/yr

 

 

here we go. :smash:

tow haul 3.pdf

tow haul.pdf

tow haul 2.pdf

tow haul 3.pdf

tow haul.pdf

tow haul 2.pdf

tow haul 3.pdf

tow haul.pdf

tow haul 2.pdf

tow haul 3.pdf

tow haul.pdf

tow haul 2.pdf

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