Hey guys, hoping maybe someone can shed some light on my issue. My 2013 GS recently through a security light and started doing some odd buggy stuff. Speedo is jumping all over the place when the light is on and also having a service traction message pop up with it. Doesn't happen all the time but becoming more frequent. I initially thought it was my recently installed throttle controller but after removing the problem remained. Not even sure where to really start. Hopefully someone can point me in the right direction. (Battery is brand new, alternator is good and I've checked all the basics). Should also note when this occurs my HP Tuners N Gauge also looses communication. So I assume this is some sort of module communication error.

 

The only thing I can suggest is putting a decent scan tool (not code reader) that can access all of the car's modules...with the service traction and speedo I'm thinking your alternator might have to much AC Ripple...did you check that when checking your alternator ??...since the wheel speed sensors (service traction message) are AC driven and also the speedo through the VSS sensor...just a guess...do you know how to check AC ripple ??

 

Not too sure on how to check for AC ripple, my buddy is suppose to bring his Tech II by tomorrow to scan it and see what we can find. I have a feeling it could be VSS related as well. It through a check engine light as well on the last drive. I haven't been able to pull the code yet as the same friend with the Tech II has my HP tuners cable. Hopefully I can get some answers based on that. How would we go about checking for the ripple?

 

Select AC VOLTS and millivolt setting if your DVOM supports it on your DVOM…negative lead on battery negative and positive lead on the B+ terminal of alternator…should be less than 0.1 volts (100mv)…run the car at 2000 RPM with a load on it…blower, headlights etc…a scope is actually better to do this test !!

 

Thanks man! We're gonna see what we can find out tonight, Ill report back!

 

Thanks !!...99.9 % of the time we never hear a resolution...this is what AC Ripple looks like on a scope...my ripple about 55Mv...this is DC millivolts using "AC Coupling" to remove all of the DC component from the waveform…excessive ripple can also cause communication issues.

 

So we didn't get a chance to test for ripple or scan it but we think we may have found the culprit, though im not entirely sure why. We we're able to pull a u0073 code Control Module Communication Bus “A” Off. with the N Gauge while it was in Run Engine Off. I drove the car around for a bit, same buggy issue. My buddy suggested just since it was having issues communicating to unhook the N gauge and see what happens. It seems like its corrected the problem. I checked the wiring to the N Gauge, cant see anything out of place but the security light went away and the car seems to be happy. Any thoughts? We still plan to scan it tonight and see if we can figure out exactly what was going on.

 

So update. We hooked my buddies MOTUS into it and couldn't get it to communicate with the ECM, BCM, or any of the other important modules but strangely we could talk to the radio, the hvac, and other stupid things like that. Unplug it the security light goes back out and it acts fine. the U0073 code went away but it seems whatever we plug into the obd2 port freaks the car out. Not sure where to proceed next.

 

I’d check the comm lines by taking a resistance reading between pins 6 and 14 from the DLC…best to disconnect the battery….you should see 60 ohms….if you see 120 you may have an open in either of the 2 comm line wires…with a voltmeter you should see about 2.5 volts on either of those 2 terminals with the battery reconnected.

 

I'll try that when I get home this evening. I appreciate all your help man, I owe ya a beer the next time I make it down to FL

 

I would also check that AC ripple !!

 

I will for sure! Much appreciated, ill keep you updated.

 

In for the fix

 

Sorry for the lack of update, haven't had a chance to get in the garage yet and check it out. Hoping to this evening or next.

 

So I finally got in the garage and was able to take a look @C5 Diag . I tested resistance across pins 6 and 14 and was only coming up with 20 ohms

 

The only thing I could tell you is starting disconnecting all those modules you could not communicate with one at a time and see if the 60 ohms returns.

 

unplug replug clean all the connections at passenger side?

 

havent had too much time to mess with it, hopefully going to dig into it a bit sunday and see what I can figure out. As frustrating as the problem is the car seems to be running find as long as nothings plugged into the port so its been hard to want to tear it appart with driving season coming to an end. I think this weekends gonna be about it though.

 

Figured I should update this thread. Somehow in the process of rewiring the fan and NPP switches I had installed under my steering wheel and moving them to the console I must have either bumped whatever was wrong and fixed it or I had some strange interference being brought on by one of those circuits. The problem has seemed to have resolved itself. N-Gauge and HP tuners connect no problem now. Strange for sure and not sure I dont trust it to happen again but its fixed for now i suppose.

 

Glad you found something...hopefully it stay's "fixed" !!...sometimes these N-Gauge doo dads can cause issues just by being plugged into the OBD2 port all the time which "technically' shouldn't be done....TSB below.


#13-08-116-001H: Aftermarket ALDL or DLC Interface Devices Causing Multiple Issues - (Sep 16, 2022) Subject: Aftermarket ALDL or DLC Interface Devices Causing Multiple Issues Models: 2023 and Prior GM Passenger Cars and Trucks Attention: This bulletin also applies to any of the above models that may be Export from North America vehicles. 
This bulletin has been revised to add the 2023 Model Year and an Important statement under Condition. Please discard Corporate Bulletin Number 13-08-116-001G.
ConditionImportant: Service agents must comply with all International, Federal, State, Provincial, and/or Local laws applicable to the activities it performs under this bulletin, including but not limited to handling, deploying, preparing, classifying, packaging, marking, labeling, and shipping dangerous goods. In the event of a conflict between the procedures set forth in this bulletin and the laws that apply to your dealership, you must follow those applicable laws.

Customers may comment on various issues with their vehicle related to high or low speed data bus traffic. These concerns may be widely varied, but some of the known issues are listed below.

The information contained in this bulletin is not meant to single out any one device or symptom, but to provide additional information that may be useful for diagnosing issues that do not have other diagnostic methods to identify the root cause.

Note: This bulletin is being written with a focus on full size truck and full size van along with other fleet vehicles, but could apply to any vehicle.

 

Known Symptoms (not specific to any one device)

• The radio may not shut off after shutting down vehicle.
• Bus or LAN traffic may stay active leading to a discharged vehicle battery.
• Problems reprogramming modules either because of interference or the device will not allow the bus to power down.
• ONSTAR® may lose the ability to provide diagnostic data.
• Various engine and transmission performance issues with SES light set.
• Intermittent driveability issues.
• Reduced power message and codes.
• Stabilitrak® message and codes.
• C0561 stored in the EBCM leading to a traction control issue.
• No high speed LAN communication along with various communication U-codes.
• Transmission may not shift for one key cycle (TCM in default mode).
• Erratic gauge readings or flickering displays.
• SES, MIL or CEL light set and numerous DTC communication codes such as U0100, U0101, U186B and U1862.
• Diesel power-up devices causing no power in 4WD low range.
• Erratic electric power steering boost potentially associated with codes U2109, U2107, U2100, B1325, C0000.
• Battery run down
• Service Tire Pressure Monitoring (TPM) system light illuminated.– Cannot relearn TPM
  
• Specific to Hybrids:
  • Reduced propulsion power message.
  • Service high voltage charging system message.

CauseIf nothing else can be identified as the root cause of the issue after normal diagnostics as found in SI, check for a device plugged into the Assembly Line Diagnostic Link (ALDL) or Data Link Connector (DLC) for tracking and/or maintenance interval scheduling. Monitoring devices, along with other electronic accessories such as aftermarket cruise control, or police speed checking devices (RADAR or LIDAR) may cause one or more of the concerns listed above.

Many of the problems described could be caused by an open connection on the HSCAN bus. Example: if the device only makes connection with one CAN +, then it will cause bus errors and erratic ECU behavior.

These devices may be removed by the customer for use in another vehicle while theirs is brought in for service. The intent of this bulletin is to identify a potential source of concerns that do not have other diagnostic methods to identify them. The examples below illustrate some of the devices encountered.

Examples:

The monitoring device examples are not specific to any one design, and styles will vary.
Device W/Secondary DLC Connector
Open In New TabZoom/PrintThis device has another DLC connector on it. The rest of the harness along with the device can be placed out of sight hidden from the technician, who may not notice the diagnostic connector is not in the factory location.
Pedal Mounted Aftermarket Device Interface
Open In New TabZoom/PrintAftermarket Device at ALDL
Open In New TabZoom/PrintAftermarket Device Switch
Open In New TabZoom/PrintMonitoring Device Example
Open In New TabZoom/PrintFleet Tracking Device Interface (May Include Rental and Lease Vehicles)
Open In New TabZoom/PrintFleet Tracking Module Plugged Into the DLC
Open In New TabZoom/PrintCorrectionIf SI diagnostics do not identify the source of the issue and if the device is available, attempt to duplicate the condition, and then remove the device to determine if the condition is eliminated.

If the customer’s concern is resolved by removing the DLC interface device, inform the customer of the results, and that they should work with the supplier of the device for further resolution.

If the condition is not eliminated with the device removed, continue diagnosing the vehicle with the appropriate Service Information.
Parts InformationThere should not be any parts required. If on the rare occasion parts appear to have been damaged by the device or the installation of the device, this would not be a defect covered under the New Vehicle Limited Warranty. For more information on Non-General Motors Parts & Equipment and Original Equipment Alterations, please refer to Article 1.2.2.12 of the Warranty Policy Information Manual. The repair order must be documented correctly stating factual information on what alteration or product was identified on the vehicle.
Labor Operation

Description

Labor Time

0600014

Suspected Tampering

0.2 hr
Warranty InformationIf ALDL interface devices are suspected as the root cause for a customer's concerns, submit a claim using the 0600014 Labor Operation to document the concern as detailed in the latest version of Corporate Service Bulletin Number #09-00-89-016: Warranty Administration - Labor Operation 0600014 - Suspected Tampering or Vehicle Modifications, including submitting the claim under the appropriate labor operation and selecting the Customer Enthusiasm indicator in Global Warranty Management.

If a claim is submitted to GM, follow all existing guidelines within the Service Policies & Procedures and GWM User Manual, GlobalConnect Messages, Bulletins or any other communication format.