A mileage of about 120,000km, equipped with model L91 inline 4-cylinder 1.6L, multi-point fuel injection, double overhead camshaft engine, and model 81-40LE 4-speed automatic transmission 2008 Shanghai General Motors produced Buick new Kayo sedan. The vehicle presses the remote control to lock the door, but there is no prompt, before the normal time the horn will sound, and at the same time the hazard warning light will flash a little. Let’s take a look at how to overhaul it!
Buick engine inspection and analysis
The fact that the horn will beep and the hazard warning lights will flash when the doors are remotely locked indicates that the vehicle has entered the body immobilizer system. According to the inspection of the central locking, horn, and hazard warning lights, the previous maintenance personnel were normal and carried out the actual test. The test is as follows: first lower the windows or a person in the car and then press the remote control to lock the doors, and finally the human pulls open the center lock to open the door, the vehicle did not issue an alarm (horn sounded, double blinking lights flashing). Accordingly, the maintenance staff initially diagnosed vehicle anti-theft system failure with the diagnostic instrument TECH2 test with no relevant fault code, and finally replaced the remote door locking anti-theft module (Figure 1). Still, after the replacement of the fault remains, the maintenance work is at an impasse.
Confirmation of the failure phenomenon again, and carrying out a variety of tests, the results are indeed consistent with the user’s description as well as the previous maintenance personnel test situation, the failure is related to the security anti-theft system. Before carrying out maintenance operations, we must have a full understanding of the anti-theft system of this model. The anti-theft system of this vehicle consists of the security anti-theft system or the car body anti-theft system (CTD) and the vehicle anti-theft system (VTD), which work independently of each other and do not interact, but only share the same LED security indicator.
These two systems work properly with signal input and execution control, it should be noted that, due to different vehicle configurations, some models canceled the right front/tailgate anti-theft switch, hood contact switch, safety indicator, and siren (changed to the traveling horn), and so on. According to previous tests, the fault of this vehicle is on the security anti-theft system (CTD), to troubleshoot the relevant faults, it is necessary to fully understand its structural composition and working principle.
(1) Understanding when the security and anti-theft system (CTD) works.
The security system provides an alarm (continuous hazard warning light flashing and siren chirping) when the ignition lock cylinder is turned with the ignition key in the event of forced entry into the doors or luggage compartment lid or engine compartment hood (door half-switch, hood contact switch monitoring), and when there is no abnormality in the doors, etc. (e.g., smashing the glass to get inside the vehicle).
(2) How to enter the security anti-theft system mode.
Ignition key screwed to the OFF (locked) position and remove the key (ignition key reminder switch monitoring), close all the doors, engine hatch, and luggage compartment lid, and press and release the door lock button on the remote control, after the doors are unlocked, the hazard warning light blinks -times and the siren beeps once, which indicates that the security and anti-theft mode is activated the LED security light blinks to indicate that it is activated.
(3) How to release the security anti-theft system mode.
When the driver’s side door is opened with the key, the left front immobilizer switch is turned on, or the “LOCK/UNLOCK” button on the remote transmitter is pressed.
The failure phenomenon of this car is not entering the security anti-theft system mode (CTD), according to the above analysis to focus on the ignition key reminder switch and the other 5 major input signals. Check all the doors, engine hatch, and luggage compartment lid have been closed, the center control locking is normal, and the ignition key is also in the OFF (locked) position and pulled out. Connect the diagnostic instrument to view the relevant data flow, according to the following path: diagnostics, a body, a rocker function to start a data list, a switch input, and enter the data list to view. For the list of the input signal of the switch, while operating while watching the data changes, and found anomalies: no matter how to operate, “the driver’s seat door key unlock switch” signal will not change, no matter in the opening and closing of the door under the state of the rocker or mechanical key to turn the lock cylinder, the signal is “off! The signal is “OFF”. This switch is the left front immobilizer switch described above, and other input signal data will change with operation.
Next, view the circuit diagram of the remote control door lock/anti-theft module (remote control door lock receiver), analysis shows that the abnormal data is mainly caused by line 1370 # and its connected parts, line 1370 # on the part “anti-theft door lock switch – driver” is also the data flow of the “driver seat”. Door key unlock switch, 0 This switch in the left front door locking machine assembly inside, so remove the left front door trim panel to pull out the locking machine wiring harness plug for testing, with a test lamp will be shorted to its No. 2 and No. 4 terminals, “the driver’s seat door key unlocking switch” data immediately from “off” to “off”. “to” on, which indicates that the switch signal control line and remote door rivets anti-theft module work is normal.
In addition, check the left front door locking machine assembly wiring harness plug did not lose poor contact and other abnormalities, so the left front door locking machine assembly disassembly test, dismantle the assembly with a wire and a multimeter connected to the assembly in the No. 2 and No. 4 terminals of the “anti-theft door lock switch a driver”, while the operation of the switch, while observing the multimeter display of the on and off situation, and found that the switch In the open and closed position are not conductive, while the normal “anti-theft door lock switch a driver” should
Fault resolution
Replacement of the “anti-theft door lock switch a driver”, the data in the data list return to normal, the vehicle’s various operating functions also return to normal, and the fault is eliminated.
The troubleshooting process of this fault case is a detour, replacing the remote control door lock/anti-theft module is a misjudgment, which is mainly due to the principle of the system application, the control strategy is not clear, resulting in the diagnosis of ideas are not clear. Therefore, to accurately and quickly find the point of failure, it is necessary to fully understand the structural principles of the system, and fully and reasonably use the functions and data of diagnostic tools.
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