The alarm has blocked the fuel pump, what should I do?

We also recommend reading the article about why the engine may have difficulty starting when hot. From this article you will learn about the main malfunctions that cause difficulties when starting a warm internal combustion engine.

According to experts who work with automotive electrical equipment, more than half of all cases of unexpected engine failures to start are directly related to car alarm malfunctions. Note that the complexity of implementing locks in this case is noticeably simpler compared to complex anti-theft solutions. This significantly increases the chances of removing the engine start lock yourself in the event of a breakdown or malfunction. Next, we will look at what the driver should do if the alarm blocks the engine from starting.

The alarm is blocking the fuel pump, how to turn it off

Engine start blocking is a function that is on the list of available options in almost any anti-theft system.
In this case, the system contains an immobilizer that identifies the owner by a special tag and allows the engine to start. Conventional car alarms that have a similar function in their arsenal can also block the engine from starting. According to experts who work with automotive electrical equipment, more than half of all cases of unexpected engine failures to start are directly related to car alarm malfunctions. Note that the complexity of implementing locks in this case is noticeably simpler compared to complex anti-theft solutions. This significantly increases the chances of removing the engine start lock yourself in the event of a breakdown or malfunction. Next, we will look at what the driver should do if the alarm blocks the engine from starting.

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Principle of operation

The engine start blocking by the alarm occurs if the anti-theft complex is equipped with an immobilizer. Often the car does not start even if there is a two-channel security system. The principle of operation of the blocker is to open the electrical circuit or supply current to elements that can affect the starting of the motor. The engine does not start or stops working after a while. The immobilizer prevents the commission of criminal acts related to disconnecting wires or disassembling anti-theft systems.

If the alarm detects a break-in attempt, it blocks all accessible components of the car. Immobilizers are activated automatically.

Engine blocking with car alarm

If there are installed anti-theft systems, electrical equipment is responsible for blocking the engine start. Immobilizers or car alarms may be faulty and cause constant or occasional failures during operation.

It should be added that the severity of the problem will depend not on the specific model or brand of car, but on the complexity of the installed anti-theft security system.

Accidental activation of the engine lock function

First of all, carefully study the displayed icons on the alarm key fob. A common cause of blocking is accidental activation of additional functions. It is also necessary to monitor the readings of the LED indicator light (if equipped) in the vehicle interior, which serves as a light indicator of the alarm status. Flashing LED lamps in most cases indicate that the anti-theft function of the immobilizer is activated in the menu.

If, after turning the key in the lock and turning on the ignition, the warning lamp blinks frequently (for example, the StarLine car alarm) before starting the engine, and a pictogram with the inscription “immo” is displayed on the key fob itself:

One way to solve the problem is to remove the key from the lock, after which you just need to press the button to open the central door lock on the key fob.
You can also get out of the car, set the alarm to security mode, then disarm it and then start the engine.

In other words, you need to make sure that the alarm operates in the normal mode that is familiar to the owner. Up to 30% of cases of engine start blocking by alarms occur due to accidental changes in program settings. The driver’s task is to disable all unnecessary functions in the settings.

Using the StarLine alarm as an example, let us note that this system has the option of “two-stage” unlocking. Activation of the function may occur accidentally; a separate icon will light up on the key fob screen. To turn it off, you must hold down button 3 on the key fob. The key fob will emit two beeps, after which button 3 is pressed once again. Then button 1 is pressed for a few seconds, then the security functions are removed;

Measures taken in the absence of startup

The car alarms offered to car owners have a variety of service functions and an additional blocking system is installed on the unit specified by the customer. This could be a starter, fuel pump, engine control unit, automatic transmission, etc. If any of the engine blocks or components suddenly refuses to function, then it is necessary to determine the cause of the malfunction by connecting diagnostic equipment.

One of the reasons for the lack of starting may most likely be a malfunction of the standard anti-theft system (immobilizer).

The principle of operation of the immobilizer, in contrast to the external anti-theft system, is based on data exchange with the control unit, allowing or prohibiting engine starting without additional interlocks. Permission to start the engine is carried out only after successful initialization (reading the code) of the attached black key. If the car is not disarmed, then when you try to start the engine, the control unit will block the ignition system and the operation of the fuel pump.

Data exchange between the immobilizer and the electronic control unit occurs via K‑Line, so it is possible to disable it by simply connecting it to the diagnostic block of scanning devices with the ignition on.

The fact that it is the external alarm system that is blocking the engine start can be determined by the blinking of the control indicator, information on the key fob monitor, the constant operation of emergency lights (side lights or headlights), freezing and inoperability of the control panel buttons and the operation of the sound bell.

Disabling locks using the service button in the cabin

If there are no signs of unintentional activation of engine start interlocks, you can try to unlock the engine using the service mode. This mode is called Valet and is used to transfer the system to service mode. To activate, you need to insert the key into the ignition, turn on the ignition and then turn it off.

After this, you need to hold the service mode activation button for about 10-20 seconds. The result will be a notification using a special short signal, after which the signal lamp (indicator light, LED) will be constantly on. This method means disabling all security functions, which may also mean removing the engine locks. We add that after fixing the problem, it is necessary to activate the security functions of the alarm again.

Independent troubleshooting of alarm systems

It is often possible to fix the malfunction and remove the engine lock yourself if you can detect blown fuses. This problem often leads to malfunctions of the alarm system. The fuses must be checked; if a problematic element is detected, the blown fuse must be replaced with a known good one.
Malfunctions in the operation of the alarm can also be associated with insufficient battery charge or loose terminals on the battery contacts. In this case, the battery is still able to sluggishly crank the starter, but the engine blocking may already work and further prevent the engine from starting.

Another step is to check the limit switches (limit switches), which are located under the hood and trunk lid. Moisture ingress or oxidation of the limit switch often causes an incorrect signal to the alarm control unit, which leads to engine blocking. Please note that unprofessional installation of alarms and limit switches, as well as improper engine washing can lead to malfunctions of electrical equipment.

Tips and tricks

If attempts to remove engine locks and start the engine are unsuccessful, then there is a high probability of a serious malfunction or failure of individual alarm elements. The result is random activation of engine locks, which cannot be disabled using standard methods. The faulty car must be taken to a service station, as removing the lock will require professional intervention.

The specified delivery can be carried out by tow truck. Another affordable way is to call an auto electrician who works on-site. Note that the final costs of paying for the service of on-site engine unlocking, disabling the car alarm, emergency opening of locks, etc. often turn out to be less than delivering the car to a service center by tow truck and paying for repairs at a technical center.

Relay for blocking the fuel pump from the alarm.

Edinochestvo » Thu Jun 04, 2015 23:19

I’ll say right away that I know almost nothing about electrics. The situation is as follows. The car had an Excellent City alarm. There was only one keychain left, and I somehow broke it. I found an advertisement for the sale of the same used alarm system. I decided to install it by stupidly moving all the contacts from one control unit to another. The new key fobs work great, but the car won't start because... the lock is activated - the fuel pump does not pump.

Tell me where to look for the fuel pump relay, and where the blocking relay may be located - directly next to the first one, or anywhere?

Doesn't start with key fob

If your car does not start with the key fob, that is, the problem is related to the autostart of the car, then if you have a temperature sensor, you need to set it to a higher temperature. Then the car will be able to warm up automatically and there should be no problems with autostart. If the starline alarm also does not allow the car to autostart, then the problem may be related to the car’s wiring. It's worth finding out how the starter in your car is connected. If the starter connection occurs in a gap, then it is worth removing it and leaving one single wire.

It is possible that the car owner has reset the settings to factory settings. In this case, you shouldn’t even be surprised that your car won’t start from autostart. When such a problem occurs, the crawler stops working because your car's chip is not showing up, and that is why the car does not autostart properly. In order to solve this problem, you must definitely visit the service center where the alarm was installed. Re-setting the car alarm will take just a few minutes for the technicians and will save you from this problem.

The alarm is blocking the fuel pump, what should I do?

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And they - these algorithms - can be passive or active. Everything is the same as with well-known “minorities” - like relays and relays - and lo and behold - it can be “passive”, or maybe “active”. It depends on the algorithm (such as, on the environment, on upbringing) who will become who and what. The active blocking algorithm is the most vulnerable, because the blocking relay with such an algorithm in a de-energized state allows the engine to start.

This type of blocking is otherwise called “normally closed”, or simply NC - according to the type of blocking relay contacts in the “Security” mode. A typical implementation diagram of the NC engine blocking is illustrated by the fragment of the connection diagram for a standard Taiwanese alarm system shown in Fig. 2 - mostly manufacturers who have narrow eyes from birth like to use NC blocking.

In the “Disarmed” mode, there is no voltage on the blocking terminal, and therefore on the relay winding, and the relay, with its NC contacts (contacts 87a and 30), allows the engine to start. More precisely, it does not prevent this. In the “Security” state, there is a ground potential on this wire, and when you try to start the engine, a plus from the ignition switch will appear at the second end of the winding, the relay will switch, thus prohibiting the operation of the starter, in this example.

To neutralize active blocking, obviously, it is enough to simply de-energize the alarm module in any way. For example, by pulling out all the connectors from the module, or simply breaking the wires, and often it is enough to remove the system fuses from the holders. And that’s it – nothing can stop you from starting the engine. This is the main reason why I can’t stand blocking NC by relay contacts.

With a passive algorithm, a blocking relay prohibits engine operation in a de-energized state; the contacts of such a relay are normally open (blocking is therefore called NR).

Unlock methods

Having installed an external alarm system, for example, Starline, it is advisable for the car owner to carefully study the instructions for the rules of its use and operation. The instructions also contain tips on what to do if there is a malfunction in its operation.

The easiest way to unlock an external alarm is to re-close the car doors. To do this, get out of the car and close the door tightly. Then turn on the remote control to arm the car and wait about ten seconds. It is during this time that the car is armed. On some types of alarm systems, the arming process takes longer, from one to two minutes.

An attempt to return parameters to factory settings using the key fob can work effectively. Due to the fact that there are very many types of alarm systems installed on cars, and at the same time the settings algorithm is also varied, resetting parameters and returning to factory settings must be carried out according to the instructions.

Situations arise when the central unit does not respond to commands sent by the key fob. In this case, you can use the Valet service button. The button may be located in a secluded place, where the hijacker will not find it and it will take time to find it through the wires.

The location of the Valet button is indicated in the description, but often installers choose its location at their own discretion. It is recommended that after installing the alarm, you check with a specialist in what place he placed it. Forgot to ask or bought a used car, and then there were problems with the signaling. No problem - the service button is easy to find along the wires coming from the central unit.

If the alarm system is blocked so that not only the engine does not start, but the doors do not open, then you need to open the door lock with the key. Opening the door will automatically trigger a loud sound alarm, which can be turned off by disconnecting the terminal from the battery. Using the dialing method or using a diagram, the terminal numbers on the central unit and the color of the wires are determined. Using this information or visually using wires with the corresponding color, we find the location of the button.

Switching to service mode (or unlocking) is individual for each type of anti-theft system. Therefore, how to use the Valet button is described in the manufacturer’s instructions. Basically, all actions are almost the same for most types of alarms.

Here is an example of Starline deactivation:

Open the car with the key.
Turn on the car's ignition and press jack three times (time limited to 20 seconds).
Turn off the ignition.
The siren will sound and the emergency lighting will turn on at intervals.
Starline deactivation is complete.
Start the engine.