So little by little and much money we are getting the H3t Road worthy. Last code left P0856. (Traction control failed / Service Stability.) I have read so many threads on here and have tried many of the suggestions but I am asking for your knowledge and help once again. 2009 H3t / I5 engine / Front & read Differential lockers. Thanks in advance. Love this truck even with all the hiccups

 

I have read so many traction fail threads on here & don't mean to beat a dead horse but after replacing the catalytic converter the check engine light is off all the other codes are gone and P0856 is left. I really want to fix this once and for all. Any help is appreciated. When the code is cleared it reappears instantly. I know it must be a serious communication problem, sensor? Computer? 2009 H3t with I5 engine and the locking differential option

 

Like the sticky thread at the top of the FAQ Sections asks, please do not post new threads in that section. Just cause you thought up a question, does NOT make it an FAQ.

Thank you.

 

 

First things first; Have you replaced the stock POS battery terminals with something better? H3s are extremely sensitive to variations in voltage, and the stock battery terminals are a well known cause of many, many, seemingly unrelated electrical gremlins/codes. It's not a matter of IF they will cause problems, it's a matter of WHEN.

Second, the Stability System/traction control errors COULD actually have nothing to do with either of those systems. Have you also gotten a "Reduced Power" message? If the engine goes into a reduced power mode, the computer automatically turns off the Stabilitrac and Traction Control systems.

 

 

Still have the service Traction control light & code P0856 but truck seems to be driving normal. Clear the code & it comes right back. I did notice the 4Wh Lock button blinking while driving temporarily the other day and then in a dirt parking lot making a hard turn the truck went into 4Wh Lock on its own. May this be a clue or reason why I still have code P0856?

 

So, what have you actually tested replaced with your system.. in direct relationship to your stabilatrac error????

I'd strongly suggest starting at the beginning... As if we don't have a clue... hahahaha. Because I have not one clue as to what you've done so far.

 

Here is a bunch of info from the web. This is not my words so credit to the original author..

What causes the P0856 code?

The P0856 trouble code is usually caused by a faulty ON/OFF switch in the traction control system. This usually is the result of spills or leakage damaging the control switch, or faulty, loose, or damaged wires, connectors, and other electrical components in the system. In addition to a defective switch, corrosion on the traction control sensor connector can cause the P0856 code to be detected. While it is rare, the traction control module may also be defective.

What are the symptoms of the P0856 code?

When the P0856 trouble code is detected, the check engine soon warning light will illuminate on the instrument cluster, and the traction control malfunction warning light will likely illuminate as well. In addition to these warnings, the traction control system is likely to stop working, which can result in a loss of grip (mainly on slippery or icy conditions). The transmission may also have a hard time shifting, or may not shift at all (and may enter limp-in mode), and the vehicle will likely experience reduced fuel economy.

How does a mechanic diagnose the P0856 code?

The P0856 code should be diagnosed using a standard OBD-II trouble code scanner. A trained mechanic will use the scanner to view the freeze frame data, and assess the code. The mechanic will also look for the presence of additional trouble codes. The codes should then be reset, and the vehicle should be restarted, to see if the code persists. If the code does not return, then it was likely triggered erroneously, or represents an intermittent issue.

If the P0856 trouble code returns, the mechanic should visually inspect the electrical components in the traction control system, to see if there are any loose, damaged, or corroded wires and connectors. All damaged components should be replaced. If the technician notices that the ON/OFF switch is damaged as well, it should be replaced.

Every time a component is replaced, the codes should be reset and the vehicle restarted before the mechanic proceeds. This will allow the mechanic to tell whether the issue has been resolved, or if there is more work to do.

Common mistakes when diagnosing the P0856 code

The most common mistake made when diagnosing the P0856 code is the failure to adhere to the OBD-II trouble code diagnosis protocol. All mechanics should follow the protocol properly, to ensure that both the diagnosis and the repair is not only properly done, but efficient as well.

It is common for the traction control module to be replaced when the only issue was a faulty ON/OFF switch or some damaged electrical components.

How serious is the P0856 code?

A vehicle with the P0856 trouble code present is still drivable. However, the vehicle’s traction control system will likely be disabled, meaning the car will not have good traction on wet or icy roads. Furthermore, unnecessary stress may be placed on the transmission, which can ultimately cause damage. Even though the car may be drivable, the P0856 code should be inspected and resolved as quickly as possible.

What repairs can fix the P0856 code?

Some possible repairs for the P0856 trouble code include:

• Replacement of wires and connectors in the traction control module
• Replacement of the ON/OFF switch in the traction control module
• Replacement of the traction control module itself

Additional comments for consideration regarding the P0856 code

The P0856 trouble code only applies to cars that have electronic traction control systems.

 

Thank you for responding Happy! I have read the above info and appreciate you sharing, When I bought the H3t I5 engine it was a mess, many codes so what have I done? So after rebuilding the transmission & front end and scanning truck the issue of Service Traction remained then found out I had a totally clogged exhaust system do to a failed Catalytic Converter since replacing that along with both O2 sensors & Throttle body the truck is finally road worthy. Before all this I had a shutter on the left front when taking foot off gas when the traction was on not when I turned it off. I no longer have that although I mostly drive with the traction off. When they refer to replacement of the ON/Off switch in the traction control module is that the switch on the dash or is it actually on the module? All codes are gone except P0856 I have no check engine light but the idiot traction light and the service memo on dash. Truck has been scanned and all systems seems to be communicating as it should. I am going back this week to scan again now that I have put miles on it. Thanks again for your help. Oh and yes I have changed the battery and terminals.