Vehicle 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 Cadenza sedan. After the vehicle locked the doors by remote control, there was no prompting, and the horn would sound once and the hazard warning light would flash at the same time when it was normal before. Let’s see how to fix it!
Buick Escalade engine inspection and analysis.
Replacement of remote door lock anti-theft module
The horn chirps and the hazard warning light flashes when the doors are locked remotely, indicating that the vehicle has entered the body immobilizer system. Front maintenance personnel according to check the central locking, horn, and hazard warning lights are normal, the actual test. The test method is as follows: first lower the windows or people in the car and then press the remote control to lock the door, the last person to pull the center lock to open the door, the vehicle did not issue an alarm (horn, double blinking lights flashing). Accordingly, the maintenance staff was initially diagnosed as having vehicle anti-theft system failure, with diagnostic instrument TECH2 test no relevant fault code, and finally replaced the remote control door lock anti-theft module, but the replacement of the fault remains, and the maintenance work is at an impasse.
CTD
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 this model’s anti-theft system. This car anti-theft system includes a security anti-theft system, or body anti-theft system (CTD), and a vehicle theft prevention system (VTD), the two systems work independently of each other, will not interact with each other, to confirm the failure phenomenon, and carry out a variety of tests, the results are indeed consistent with the user’s description and the previous maintenance personnel test situation, the failure is related to the security anti-theft system. Before carrying out maintenance operations, we must fully understand this model’s anti-theft system. 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 executive control as shown in Figure 2, it should be noted that, due to different vehicle configurations, some models canceled the right front/tailgate anti-theft switches, hood contact switch, security lights and sirens (changed to the traveling horn) and so on. According to the previous test, this vehicle fault is in the security anti-theft system (CTD), to troubleshoot the relevant faults, we must fully understand its structural composition and working principle as follows.
She was understanding when the security and anti-theft system (CTD) works.
The security and immobilizer system can provide 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 access to the door luggage compartment lid or engine compartment hood (door half-switch, hood contact switch monitoring) and when the doors, etc., are not abnormal (e.g., smashing the glass to gain access to the interior of the vehicle).
How do I get into 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.
How to disengage 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 malfunction phenomenon of this car is that it does not enter the security anti-theft system mode (CTD), according to the above analysis to focus on checking the center ignition key reminder switch and other 5 major input signals. Check all the doors, engine hatch, and luggage compartment lid have been closed, the center control lock 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 is 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 the remote control door rivet anti-theft module work is normal.
In addition, check the left front door locker assembly wiring harness plug did not lose poor contact and other abnormalities, so the left front door locker 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 is not conductive, while the normal “anti-theft door lock switch a driver” should be in the closed position is not conductive, in the open position is conductive, it is clear that the “anti-theft door lock switch a driver” there is a failure.
Troubleshooting
Replacement of “anti-theft door lock switch a driver”, the data in the data list returned to normal, the vehicle’s various operating functions also returned to normal, the fault is eliminated, review and conclusion!
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 application of the principle of this system, the control strategy is not clear, resulting in unclear diagnostic ideas. 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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