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Dead LPG switch, the car does not start ... Peugeot 406, 2006, BRC gas installat

meschkis 16818 11
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  • #1 16833488
    meschkis
    Level 8  
    Posts: 13
    Rate: 3
    Hello!

    I need help,
    the situation looks like this:

    I own a Peugeot 407 car, 2.0 petrol 140 HP + LPG BRC purchased about a week ago from "dark-skinned Germans"
    The gas switch is dead, and the car does not start, as if the LPG system has died, cutting off the fuel pump ..
    what to do ???


    For more insightful detailed description below:

    The car in the morning usually had to turn on longer to start (probably candles I thought), sometimes as if it mucked up a little when reaching the intersection and turning ... as if the fuel was disturbed in the tank.
    I thought it was the fault of the automaton, which after braking reacts slowly to gas (half full tank, about 75% gas)
    it happened that the car after driving 4-5 km and a short stop (buying cigarettes at the station) went out after driving off and it was difficult to start - I thought that the gas turned on too early and may choke when starting.
    One morning the car was quite hard (the third time), but it started, later switched to gas and everything was ok ...
    the first stop and after a few minutes of parking fired, then after a few meters it went out, it was hard to fire but it got on and you could go on. The next stop, the longer one and the problem with firing but again it managed. I had the impression that on the stretch of about 30 km twice as if there was no fuel for a moment and again it was OK.
    Last stop, about 30 minutes and it was impossible to fire.
    During the first few attempts of firing, when the ignition was switched on, the upper green indicator of the gas switch appeared (for about 1-2 seconds), hold-down for longer (for emergency firing on gas) had no effect, the diode simply went out.
    After some time, the attempt to start the car looked like this: ignition, gas switch dead, no solenoid valves or fuel pump can be heard, the starter turns, the car does not start ... I unplugged the clamps for a few minutes - did not help,
    I unhooked the gas central - nothing too ...
    I went out of my way, I tried to leave the car with the clamps unfastened for a long time (about 30 minutes), someone somewhere said that as long as it does not require miracles, I also connected the clamps from another car, I watched the fuel pump - what's interesting, feel a leak Pb fragrance.
    finally I read that the "N" automat can be towed up to 30 km, 30 km / h ...
    So the car is under the house, it would be nice to get any advice (I'd like to go to the parking lot and check)
    I know that topics are discussed in this forum, which for the layman are often magic or space, so I'm sure that in my situation you can definitely do something, it looks like a shit and I plan to stick to it ... ;)
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  • Helpful post
    #2 16833499
    motyl7104
    Level 17  
    Posts: 152
    Help: 24
    Rate: 34
    Start by checking the lpg driver power supply. There are two pros, one directly from the battery with a fuse, often it becomes black or breaks off. The second is the plus on the key. No and the weight at the battery.
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  • #3 16834191
    meschkis
    Level 8  
    Posts: 13
    Rate: 3
    Dead LPG switch, the car does not start ... Peugeot 406, 2006, BRC gas installat Hello!
    I just got back from the parking lot, the situation is this: I unplugged the driver and checked the voltage with the meter, black is minus, red - constant plus, green is the same thickness as the other two and there is no voltage on it, regardless of ignition. The problem is that I can't locate the fuses for anything, everything is wrapped in black insulation that doesn't look good ...
    Question: can I try to connect the battery plus directly to this cable to check if the installation came alive?
    or maybe this way I risk burning the driver?
    the situation is quite tense because I have to get to work in the morning.
    In the picture I have located only one fuse, it looks good, besides, the voltage is positive.
    https://obrazki.elektroda.pl/1686782900_1511093968.jpg
    Dead LPG switch, the car does not start ... Peugeot 406, 2006, BRC gas installat
    https://obrazki.elektroda.pl/3390742600_1511094146.jpg
    One more thing ... is this loose yellow cable "supposed to be"? you can't see it disconnecting from somewhere

    Added after 1 [hours] 29 [minutes]:

    I tried to connect "briefly"
    I heard the solenoid valve and what's more, the smell of gas and hissing on the hose from the reducer to the filter on the way to the strip ...
    Is it possible that the installation included gas and gasoline?
  • #4 16834875
    motyl7104
    Level 17  
    Posts: 152
    Help: 24
    Rate: 34
    yellow is probably from the lambda sensor, it may not be connected. If you leak, you should be very careful. It can disconnect gas if the pressure drops through it but does not disconnect gasoline. The problem is probably with the motor control, maybe the shaft position sensor. To completely exclude lpg installations, you still need to disconnect the gasoline injectors, and connect directly to the ecu harness. Alternatively, look for the wires at the lpg bundle and short-circuit.
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  • #5 16834972
    meschkis
    Level 8  
    Posts: 13
    Rate: 3
    I corrected the leak, shortened the hose and gave a new clamp, after another attempt the leak appeared on the same hose, only at the filter this time.
    After connecting this green cable for a short time
    Installation still shows no signs of life (switch)
    The solenoid valve can be heard clearly, I had the impression that the pump turned on for a while ..
    Interestingly, this leak in the gas and the top of the pump also feel gasoline, it looks like the pressure was from both installations, only something further was closed ...

    Added after 2 [hours] 13 [minutes]:

    Could someone suggest how to disconnect this installation so that the car can only run on gasoline?
  • #6 16838427
    meschkis
    Level 8  
    Posts: 13
    Rate: 3
    meschkis wrote:

    Could someone suggest how to disconnect this installation so that the car can only run on gasoline?

    I meant whether it is possible to switch injections in some way without interfering with the wires, because this beam looks really uninteresting.
    maybe the photo will help ...
    Dead LPG switch, the car does not start ... Peugeot 406, 2006, BRC gas installat
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  • #7 16838586
    Pawel wawa
    VIP Meritorious for electroda.pl
    Posts: 16093
    Help: 1262
    Rate: 4416
    First of all, stop creating any bridges, short circuits and giving power for a short time. secondly, the gas controller has some designation. Submit them to the forum. After marking it, download the diagram from the network and check the power supply and mass.
  • #8 16838855
    meschkis
    Level 8  
    Posts: 13
    Rate: 3
    It was possible to take such a photo of the driver:
    Attachments:
    • Dead LPG switch, the car does not start ... Peugeot 406, 2006, BRC gas installat 20171119_130104.jpg (664.43 KB) You must be logged in to download this attachment.
  • #9 16838862
    meschkis
    Level 8  
    Posts: 13
    Rate: 3
    I was looking for a schema for BRC seqenc 24, this designation is on the interface cube, but the schema does not tell me much
    I ordered a diagnostic tool, maybe the computer will show you what the problem is regarding gasoline supply, because the check is on.
    I hope it will come today.

    Added after 4 [hours] 37 [minutes]:

    Pawel wawa wrote:
    check power and ground.

    Is this synonymous with plugging in with a cable with a meter tip?
    I've already done it ... on red is + permanent ..
    There is no key on the green.
  • #10 16845300
    meschkis
    Level 8  
    Posts: 13
    Rate: 3
    An OBD device has arrived.
    Shows error of coils A, B, C and D.
    What can be responsible for all coils at once?
    I suspect that this may be due to a lack of power for the LPG system
  • #11 16845751
    Pawel wawa
    VIP Meritorious for electroda.pl
    Posts: 16093
    Help: 1262
    Rate: 4416
    The fuse is burnt (or the connection on the LPG pipe rotten), from this coil power supply you also have the gas central power supply connected - after ignition :)
  • #12 16846080
    meschkis
    Level 8  
    Posts: 13
    Rate: 3
    Will you tell me how can I locate it?
    A few posts above I added a photo from under the mask ..
    I hope it will be .. ;)

    Added after 10 [hours] 28 [minutes]:

    Was close..
    it turned out that after giving + to the fuse in the engine compartment box the car was asking ...
    There are two fuses: number 5 and number 10
    With the help of internetworkers I was able to trace the cause ..
    This is the BSM module, or only its BSF1 relay, which I will verify in the morning ..
    What gas check later ...
    Thank you for your commitment.

Topic summary

✨ The discussion revolves around a Peugeot 407 with a BRC LPG installation that fails to start due to a dead LPG switch. The owner describes symptoms including difficulty starting, potential fuel delivery issues, and a suspected malfunction in the LPG system. Responses suggest checking the LPG driver power supply, fuses, and connections. The owner investigates the wiring and fuses, ultimately discovering issues with the BSM module and relays. Diagnostic tools reveal errors related to ignition coils, indicating a possible lack of power to the LPG system. The owner is advised against creating short circuits and is encouraged to trace the wiring for proper diagnosis.
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FAQ

TL;DR: On BRC Sequent systems the LPG ECU needs two power feeds; “Start by checking the LPG driver power supply.” Fixing the missing ignition-switched feed or a blown fuse often revives a dead switch and restores starting. [Elektroda, motyl7104, post #16833499] Why it matters: If the LPG ECU loses its key-on feed, it can mimic a fuel-pump or ignition failure and strand you.

Quick Facts

How do I fix a dead LPG switch and no-start on a Peugeot 407 with BRC Sequent?

Verify the LPG ECU has both power feeds. Check constant battery +12 V and the ignition-switched +12 V at the ECU harness. If the ignition feed is missing, trace its fuse and connection. Restore that feed and recheck the switch. “Start by checking the LPG driver power supply.” [Elektroda, motyl7104, post #16833499]

Which fuse numbers were involved in this real case?

In this thread’s Peugeot 407 case, the engine-bay box had two relevant fuses: #5 and #10. The owner found the car started after reapplying +12 V at that box and later traced it to the BSM module, focusing on the BSF1 relay. [Elektroda, meschkis, post #16846080]

Why do I get coil faults A, B, C, and D all at once?

A single blown or corroded ignition-supply fuse can knock out the coil power and the LPG ECU simultaneously. That yields coil A–D diagnostic trouble codes together and a dead gas switch. “From this coil power supply you also have the gas central power supply connected.” [Elektroda, Pawel wawa, post #16845751]

What first symptoms suggest the ignition-switched feed is missing?

The top green LED lights for 1–2 seconds at key-on and then goes dark. You hear no fuel pump or LPG solenoids. The starter cranks, but the engine won’t fire. Long-press emergency gas start does nothing in this state. [Elektroda, meschkis, post #16833488]

Is it safe to ‘bridge’ power to the LPG ECU to test it?

No. Avoid ad‑hoc jumpers and shorting to +12 V. You risk controller damage and gas leaks. As one expert warned: “Stop creating any bridges, short circuits and giving power for a short time.” Diagnose by diagram and meter instead. [Elektroda, Pawel wawa, post #16838586]

What are the two +12 V feeds on BRC Sequent 24?

One is constant +12 V from the battery (fused near the battery). The second is +12 V with ignition on. Check both with a multimeter at the ECU connector along with ground at the battery. Restore any failed fuse or corroded joint. [Elektroda, motyl7104, post #16833499]

Why did emergency start on gas not work?

Emergency start requires a live ECU and solenoids. If the ignition-switched +12 V feed is absent, the ECU stays inactive, so long‑pressing the switch does nothing. The brief LED flicker confirms power dropout, not a valid gas start. [Elektroda, meschkis, post #16833488]

Could a gas leak cause the engine to stall and not restart?

A leak near the reducer or filter is dangerous and can drop rail pressure, forcing gas shutdown. It does not cut petrol, but combined with power loss you can get stalls and no‑start. Fix leaks before further tests. [Elektroda, motyl7104, post #16834875]

How can I temporarily run only on petrol to isolate LPG faults?

Do not cut random wires. Use the LPG wiring diagram, confirm the ignition feed fault, and restore factory injector continuity at the ECU harness if accessible. The safer path is repairing the supply, then testing petrol start. [Elektroda, Pawel wawa, post #16838586]

What is the BSM and BSF1 in a Peugeot 407 context?

BSM is the engine‑bay fuse/relay module. In the case discussed, its BSF1 relay and fuses #5 and #10 were investigated after reapplying +12 V brought the car to life. Focus diagnostics there when ignition feed drops. [Elektroda, meschkis, post #16846080]

I measured +12 V constant, but zero on the green ignition wire—what next?

Trace the ignition-switched circuit to its fuse and relay in the engine-bay box. The thread’s owner couldn’t find fuses at first due to taped looms, then discovered the engine started when +12 V was reapplied at the box. [Elektroda, meschkis, post #16834191]

What does a brief LED, then stall after a short stop, indicate?

Intermittent ignition feed can cause stalls after short stops and hard restarts. The LED’s 1–2 s glow at key-on, occasional misfires, and abrupt shutdowns match that pattern before complete failure. Repair the ignition feed path. [Elektroda, meschkis, post #16833488]

How do I perform a safe 3‑step check of the LPG power supply?

  1. Measure battery +12 V and ground at the LPG ECU connector.
  2. Turn ignition ON and verify the ignition-switched +12 V.
  3. If missing, inspect the fuse near battery and the key-on source fuse. [Elektroda, motyl7104, post #16833499]

Does towing help a Peugeot 407 automatic (“N”) with this issue?

Towing may move the car, but it won’t fix a lost ignition feed to the LPG ECU or coils. The poster towed home and still had to restore the engine-bay supply path to start. Address power and fuses first. [Elektroda, meschkis, post #16833488]

I smelled petrol and LPG near the pump area—what does that imply?

Pressure may exist in both petrol and LPG lines while a downstream control remains closed. With a dead ECU feed, neither system completes fueling. Repair leaks, then restore the ignition feed and retest starting. [Elektroda, meschkis, post #16834972]

What diagnostic tools helped in this case?

An OBD reader revealed coil faults A–D together. That clue, combined with a dead LPG switch, led to the shared ignition-supply path, fuses #5 and #10, and the BSM/BSF1 relay focus. [Elektroda, meschkis, post #16845300]
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