Hello!
2007, H3x. around 90~k miles.

Once in a while when I turn on ignition, on dashboard, stabilitrak/traction control light comes on.
(image stolen from internets, forgot to snap a picture.)


I can't tell exact pattern, sometimes this message will go away if I turn off car and turn back on, or when I wait for car to warm up then turn off/on, this light disappears.
Service 4 wheel drive message is always on.

Error codes:
B2745 - Body control module - Traction control switch circuit
B2725 - TCCM - Mode switch circuit malfunction

Before I go on shopping spree for new switch circuit, is there anything else I could look into?
As always, problems can and will be somewhere else.
White light behind 4HI burned out at some point.
Multiple lights started to burn out(slowly, during last year, one by one), door controls, climate control(some still work), maybe it is just because age?

I can switch 4 wheel modes fine, most of the time.
Sometimes I can't, then I clear codes and they work again.

Will try to learn to monitor voltage from switch, maybe something off there.

Battery is new, few months old, battery connectors are fresh and not OEM.

Thanks and have a nice day!

 

HUMMER DTC B2725

Make:HUMMERCode:B2725 Definition:ATC Mode Switch Circuit Malfunction Description:Ignition ON. System voltage 9-18 V.Cause:

• The TCCM constantly monitors the voltage on the switch signal circuit.
• If the system detects a voltage level under 0.3 volt or greater than 0.5 volts for 600 seconds, the DTC is logged.

HUMMER DTC B2745

Make:HUMMERCode:B2745Definition:Traction Control Switch Circuit Description:Ignition ON.

• Cause:The BCM detects low voltage on the traction control signal circuit for 60 seconds.

PIP5094
When testing any circuit for open or continuity/ resistance, it is imperative that all related terminal pin fit and tension be checked when the test steps require disconnection of the connector or component, prior to any component replacement.

 

umm ok.
I can only share my experience from working on this matter for months on and off with the miss' H3.
The rear wheel speed sensors and the front hubs both have to be functioning to have the system operate correctly.
We replaced the front hubs (they needed it both went bad) and we replaced the back wheel speed sensors.
Checked the wiring for continuity from each sensor back. It is a common problem that the main wiring can deteriorate nearest the plug areas.
Finally as a last ditch effort we took it to dealer ( i loath dealerships hahah). They ended up determining a bad TCCM. Talk about pricey though.
The bill was like $700+.
I would have done the swap myself but the cost to purchase the unit and install was only a couple hundred different and my honey was piszed...
It worked right up till she hit a dear doing freeway speeds.

 

Thanks for replies!
Thanks for hint with wheel sensors!
I will start with low tech voltage testing for now, will check sensors and switch circuit.

Long term plan is to get GM Tech2 compatible tool so I can diagnose everything little bit more efficient.

 

PIP4161
Subject: Service 4WD Light On and The System Inoperative, Switch Contamination Models: 2006-2008 Hummer H3
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

Some customers may comment about a Service 4WD Light on and transfer case or rear differential lock system inoperative. Technicians may find various switch DTCs or open fuses and the transfer case select switch contaminated

Recommendation/Instructions:

A number of 4WD switches have been received through the Warranty Parts Center that show obvious signs of contamination caused by liquids being spilled through the HVAC vents. On an H3 vehicle these liquids will run in behind the IP face plate and leak into the 4WD switch, the radio and if severe enough may also cause various fuses to become open.

In particular, liquid air fresheners that clip onto the HVAC vents can spill onto the IP components. Air fresheners will chemically blister the paint on the 4WD switch and cause the buttons to stick. A B2725 or B0790 switch DTC may be set. The switch may also smell like perfume. Additional paint blistering may occur on the radio.

The affected components will have to be replaced. However, contamination of this nature does not constitute a defect in materials or workmanship for which General Motors would be responsible. Each suspect vehicle should be carefully inspected and a decision made at the local level regarding GM participation with the repair expenses.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

DTC B2745

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

TCS Switch Signal Circuit

B2745 Traction control cannot be manually disabled.

Circuit/System Description

The driver may disable the Traction Control System (TCS) by pressing the traction control switch. The body control module (BCM) supplies a 12-volt signal on the traction control signal circuit. When the traction control switch is pressed, this voltage signal is grounded.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The BCM detects low voltage on the traction control signal circuit for 60 seconds.

Action Taken When the DTC Sets

• The BCM sends a serial data message to the electronic brake control module (EBCM) informing the EBCM that the desired TCS state cannot be determined.
• The EBCM defaults the TCS status to enabled.

Conditions for Clearing the DTC

The DTC clears automatically from Current status when the fault is corrected. Use a scan tool to clear the DTC from history status.

Diagnostic Aids

An intermittent short to ground on the traction control signal circuit is the most likely cause of a history DTC when no problem is found. When the Conditions for Setting this DTC are present, the driver is not able to disable traction control.

Circuit/System Testing

⇒X If DTC B2745 does not reset, go to Diagnostic Aids.

1. Turn OFF the ignition for 5 seconds, then turn ON the ignition and wait at least 60 seconds.
2. Turn the ignition OFF. Disconnect the traction control switch harness connector. Turn the ignition ON and wait at least 60 seconds.
3. If DTC B2745 does not reset, replace the traction control switch.
4. If the DTC B2745 resets, check the TCS switch signal circuit for a short to ground or replace the BCM.

 

 

Wow, thanks hummerz!
So, possible my switch button is shot.
I was looking at live data and my TCS switch state was always "Pressed".
I have "B0790" also, did not mentioned it as thought it was something unrelated, sorry...



Will run some resistance test trough it.



If it is shorted, then short term fix would be to soldier it off.

 

does the button move or stuck? compare travel/rebound to other buttons. just like a keyboard .. Did you disconnect and clean with contact cleaner? make sure contacts are clean and make sure dry before reconnect. GL

 

Button is not stuck, travels just like others.
Tested on resistance, looks like it is fine.
By pressing switch circuit was closed.


Tested with this to the ground, there is no short(if that is correct way to test it).

Next step is to figure where this cable ends at exactly, will go from there.

Edit:
"The driver may disable the Traction Control System (TCS) by pressing the traction control switch. The body control module (BCM) supplies a 12-volt signal on the traction control signal circuit. When the traction control switch is pressed, this voltage signal is grounded."
Will need to test if there is actual 12 volts coming in!
For next time.

Edit, edit:
Test "Channel P Encoder Signal" if voltage is supplied at all there.
If I understand correctly, Each Channel is supplied 5volts, when switch is pressed, specific resistance is applied and voltage is sent back to "Switch Signal"(A6).
Still learning.

 

Clear codes, disconnect switch, koeo, wait a minute, then check/post ALL current codes.