Trouble Shooter - MOTOR · something other than your scanner has been plugged into the ALDL ......
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Information Highway Turnoff Perhaps you’re familiar with the insurance plans now being offered by some insurance companies. These plans involve plugging a data recorder into a vehicle’s Assembly Line Diag- nostic Link (ALDL) connector or Data Link Connector (DLC), then collecting data from the vehicle’s management systems while the ve- hicle is being driven. This “snapshot” gives the insurance company a better understanding of how the insured vehicle is being used. As an in- centive for his cooperation, the company may be willing to offer the customer a more attrac- tive rate on his policy. This is just one example of how data from the DLC can be used in ways that may not have been envisioned originally by the vehicle manufacturer. In addition to the data recorder I just described, other applications may include a device with a secondary DLC connector, with another DLC connector attached to it. The rest of the harness along with the device itself may be hidden out of sight, and you may not notice that the diagnostic connector is not in the facto- ry location. A pedal-mounted device may be used to monitor pedal position and collect oth- er data via the DLC. An aftermarket switch, monitoring device or fleet tracking interface also may be attached to the DLC directly or may be tapped into its wiring. If properly designed, one would hope that add-ons of this sort would be benign. But an outside component “pinging” the PCM for in- formation on a regular basis may have conse- quences that are both unpredictable and unde- sirable. GM has identified several problems that may be connected to these devices and has issued a service document to address them. The focus of the bulletin is on 2006-14 GM passenger cars and trucks, with a special em- phasis on full-size trucks, vans and other fleet vehicles, as these vehicles are most likely to have monitoring devices installed. But the in- formation could be applicable to all vehicles equipped with a DLC, as any of them could have had a monitoring or reporting device in- stalled at some point, for one reason or another. The following are known symptoms, as identi- fied by GM. Some are specific to GM vehicles. Certainly there will be others that will be identi- fied that are specific to vehicles from other man- ufacturers. No single add-on device has been linked to a specific symptom. The purpose of this list is to provide information that may be useful for diagnosing issues that do not have oth- er diagnostic methods to identify the root cause. •Customers may comment on various issues with their vehicles related to high-speed or low-speed data bus traffic. •The radio may not shut off after shutting down the vehicle. •Bus or LAN traffic may stay active, leading to a discharged vehicle battery. •You may experience problems reprogram- ming modules, either because of interference or because the device will not allow the bus to power down. •OnStar may lose the ability to provide diag- nostic data. •The customer may experience various en- gine and transmission performance issues with the SES light set. Karl Seyfert In the information age, even the data generated by our vehicles has value. But the methods used to collect that information may have unintended effects on vehicle operation and service. [email protected] Trouble Shooter Photo: Karl Seyfert 6 April 2014 continued on page 8 It might not be as easy to spot as the example shown here, but if something other than your scanner has been plugged into the ALDL connector or tapped into its wiring, it may be responsible for some otherwise difficult or impossible-to-diagnose vehicle behaviors.
Transcript of Trouble Shooter - MOTOR · something other than your scanner has been plugged into the ALDL ......
Information Highway TurnoffPerhaps you’re familiar with the insuranceplans now being offered by some insurancecompanies. These plans involve plugging a datarecorder into a vehicle’s Assembly Line Diag-nostic Link (ALDL) connector or Data LinkConnector (DLC), then collecting data fromthe vehicle’s management systems while the ve-hicle is being driven. This “snapshot” gives theinsurance company a better understanding ofhow the insured vehicle is being used. As an in-centive for his cooperation, the company maybe willing to offer the customer a more attrac-tive rate on his policy.
This is just one example of how data fromthe DLC can be used in ways that may nothave been envisioned originally by the vehiclemanufacturer. In addition to the data recorderI just described, other applications may includea device with a secondary DLC connector, withanother DLC connector attached to it. The restof the harness along with the device itself maybe hidden out of sight, and you may not noticethat the diagnostic connector is not in the facto-ry location. A pedal-mounted device may beused to monitor pedal position and collect oth-er data via the DLC. An aftermarket switch,
monitoring device or fleet tracking interfacealso may be attached to the DLC directly ormay be tapped into its wiring.
If properly designed, one would hope thatadd-ons of this sort would be benign. But anoutside component “pinging” the PCM for in-formation on a regular basis may have conse-quences that are both unpredictable and unde-sirable. GM has identified several problemsthat may be connected to these devices and hasissued a service document to address them.The focus of the bulletin is on 2006-14 GMpassenger cars and trucks, with a special em-phasis on full-size trucks, vans and other fleetvehicles, as these vehicles are most likely tohave monitoring devices installed. But the in-formation could be applicable to all vehiclesequipped with a DLC, as any of them couldhave had a monitoring or reporting device in-stalled at some point, for one reason or another.
The following are known symptoms, as identi-fied by GM. Some are specific to GM vehicles.Certainly there will be others that will be identi-fied that are specific to vehicles from other man-ufacturers. No single add-on device has beenlinked to a specific symptom. The purpose ofthis list is to provide information that may beuseful for diagnosing issues that do not have oth-er diagnostic methods to identify the root cause.
•Customers may comment on various issueswith their vehicles related to high-speed orlow-speed data bus traffic.
•The radio may not shut off after shuttingdown the vehicle.
•Bus or LAN traffic may stay active, leadingto a discharged vehicle battery.
•You may experience problems reprogram-ming modules, either because of interferenceor because the device will not allow the bus topower down.
•OnStar may lose the ability to provide diag-nostic data.
•The customer may experience various en-gine and transmission performance issues withthe SES light set.
KarlSeyfert
In the information age, even the data generated by our vehicles
has value. But the methods used to collect that information may
have unintended effects on vehicle operation and service.
Trouble Shooter
Ph
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Ka
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eyfe
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6 April 2014
continued on page 8
It might not be as easy to spot as the example shown here, but ifsomething other than your scanner has been plugged into the ALDLconnector or tapped into its wiring, it may be responsible for someotherwise difficult or impossible-to-diagnose vehicle behaviors.
THE BEST
Trouble Shooter
8 April 2014
•The customer may experience in-termittent driveability issues.
•Reduced power message andcodes may be recorded.
•A Stabilitrak message and codesmay be recorded.
•DTC C0561 may be stored in theEBCM, leading to a traction controlissue.
•No high-speed LAN communica-tion, along with various communica-tion U-codes.
•The transmission may not shift forone key cycle (TCM in default mode).
•Erratic gauge readings or flicker-ing displays.
•The SES, MIL or CEL light mayset and numerous DTC communica-tion codes such as U0100, U0101,U186B and U1862 are stored in sys-tem memory.
•Diesel power-up devices may beaffected, causing no power in 4WDlow range.
•Erratic electric power steeringboost may be experienced, potentiallyassociated with codes U2109, U2107,U2100, B1325, C0000.
•The Service Tire Pressure Moni-toring (TPM) system light may be illu-minated and the system may be un-able to relearn TPM.
•Hybrid vehicles may display a Re-duced Propulsion Power message or aService High Voltage Charging Systemmessage.
Many of the problems describedhere could be caused by an open con-nection on the HSCAN bus. For ex-ample, if the device makes connectionwith only one CAN+, then it will causebus errors and erratic PCM behavior.
GM advises to look for DLC add-onsif you can’t identify the root cause of anissue by conventional means. They fur-ther advise you to check for a deviceplugged into the ALDL or DLC fortracking and/or maintenance intervalscheduling. Monitoring devices, alongwith other electronic accessories suchas aftermarket cruise control, or policespeed checking devices (RADAR orLIDAR) may cause one or more of theconcerns listed above. A better practicemight be to check for add-ons duringyour preliminary diagnostic work. Bet-ter to find something that looks out of
the ordinary at the beginning, ratherthan at the end, of a very long diagnos-tic session.
If your shop works on fleet vehicles,there may be an added wrinkle to thisstory. Let’s imagine a customer brings avehicle to your shop, complaining ofone of the symptoms described above.Unbeknownst to you, he has removedthe DLC add-on before bringing thevehicle in for service. Perhaps the de-vice was needed for another vehicle orit was removed for some other reason.Now the very thing that’s been causinga problem is not present and you mayor may not be able to retrieve any ofthe information related to the originalproblem. Imagine how frustrating thatwould be. This should provide a power-ful incentive for conducting a carefulinterview with the customer and askingwhether any devices of this sort arenow or have evert been installed on thevehicle. This preliminary step couldsave you a ton of unnecessary grief.
If it has been determined that aDLC interface device is installed, at-tempt to duplicate the condition withit in place, then remove the device todetermine if the condition is eliminat-ed. If the customer’s concern is re-solved by removing the DLC interfacedevice, inform the customer of the re-sults. He’ll need to work with the sup-plier of the device for further resolu-tion. If the condition is not eliminatedwith the device removed, continue di-agnosing the vehicle using the appro-priate service information.
We can expect problems of this sortto increase in the future. The wires ina vehicle no longer carry only batterypower and ground. Today they maycarry reference voltages, bias voltages,network communication signals and somuch more. The problems describedthus far resulted from the installationof devices that were not intended todo harm and were installed properly.We’ve all had to diagnose problemscaused by a well-intentioned accessoryinstaller who has accidentally tappedinto the wrong wire on a vehicle.These problems will only grow incomplexity on vehicles that are actual-ly very sophisticated computer net-works on wheels.
Circle #9
