P38 alarm fault

Blobthebuilder · Mar 12, 2020

OK I'm back loli was intermittently getting alarm fault and alternator fault then it went to permanent alarm fault I've changed to hankook battery and changed interior sensor and nothing changed so I disconnected battery for few mins and it lasted 10-12 times then started again, it always locks/unlocks fine from key or each fob but as soon as key inserted into steering lock it says alarm fault but goes off when key turned and if I superlock doors it chirps for door mislock but says alarm fault on dash, I also armed superlocking while in car then jumped around like a loon and it never activated alarm and I've also disconnected sounder and made no difference so I'm looking on here for inspiration now lol, TIA

brianp38dse · Mar 12, 2020

First thing never arm super-lock you could end up in a world of pain, it is known to fail on and involves cutting thing about to get the doors open.

Blobthebuilder · Mar 12, 2020

I usually don't I just wanted to know if I could trigger alarm to see if it was sensor but I was having a fiddle erlier and no matter what is put into ignition it says alarm fault so I'm wondering if I disconnect the white plug so it doesn't know key is in will it stop fault showing because the alarm seems to be (dis) arming fine

romanrob · Mar 12, 2020

Sounds to me like your alarm is never actually arming due to one/ more sensors not reading right. Hence you can jump around in the vehicle no problem, it unlocks no problem, and when you put the key in the ignition it's just giving you the courtesy message about the alarm before allowing you to drive away. As to which sensor - above my pay-grade, although I would start with micro switches and door ajar switches. There is an Alarm disable function in BeCM - that will probably get rid of the pesky message for you - otherwise you may need to go chasing sensors for a fully functioning alarm - nanocom will help you identify the states (12v/ GRND) of the various switches and spot if something looks odd.

Blobthebuilder · Mar 12, 2020

So if it's a courtesy message should I worry about door not unlocking or car not starting also light flashes on dash as if its armed

Blobthebuilder · Mar 12, 2020

Also rear passengers window will not set at all would it impact the alarm

Datatek · Mar 13, 2020

Blobthebuilder said:
Also rear passengers window will not set at all would it impact the alarm

If you are getting a miss lock message, a door, the boot or the bonnet has a switch that is not making contact correctly so the BECM thinks a door is not fully closed, the alarm will not operate correctly with this problem.
The bonnet switch is a common problem but I'm not sure that gives a miss lock message.

Blobthebuilder · Mar 13, 2020

It's not displaying any message bud

Datatek · Mar 13, 2020

Blobthebuilder said:
Also rear passengers window will not set at all would it impact the alarm

Blobthebuilder said:
It's not displaying any message bud

Sorry, you said you get a chirp for a miss lock and the alarm message. Investigate that and the window not setting.
Diagnostics would most likely give you the answer.

kermit_rr · Mar 13, 2020

Re. the spacial sensors, they don't arm unless you superlock

Grrrrrr · Mar 14, 2020

kermit_rr said:
Re. the special sensors, they don't arm unless you superlock

The ultrasound ones?

kermit_rr · Mar 14, 2020

Grrrrrr said:
The ultrasound ones?

yeah, i meant spacial! not special, changed that

Blobthebuilder · Mar 14, 2020

Just found this in rear it's tapped into the purple wire in car loom on drivers side and to earth I believe its a GPS tracker with 6v battery backup, will it have any impact on alarm system

kds · Mar 15, 2020

Dont know about on the car but when a friends house alarm battery went down the alarm went off at random times even thought battery was only meant for backup on power cuts.

Grrrrrr · Mar 15, 2020

kds said:
Dont know about on the car but when a friends house alarm battery went down the alarm went off at random times even thought battery was only meant for backup on power cuts.

Same on the miggy. The backup sounder on that had rechargeable batteries like you find in an old Tamiya RC car. Maplin had replacement ones.

Blobthebuilder · Mar 15, 2020

Update it was a grp tracker in back long since dead and I removed both rear door cards and swapped just the motor before rear driver set and rear passengers wouldn't now rear passengers sets and rear drivers won't do it appears the motor is at fault also if I lock car sitting inside the lift up inside lock and open door the alarm sounds so the alarm itself is working so I'm wondering if it's the replacement sensor faulty aswell

Grrrrrr · Mar 15, 2020

Blobthebuilder said:
Update it was a grp tracker in back long since dead and I removed both rear door cards and swapped just the motor before rear driver set and rear passengers wouldn't now rear passengers sets and rear drivers won't do it appears the motor is at fault

Motor? The lock actuator motor? Early ones are the same as those used in the MGF of the same year. Just clip in or out. Not sure about later ones but probably the same.

Blobthebuilder · Mar 15, 2020

They have a screw at top and bottom and some kind of circuitry inside but motor does fit either side

Blobthebuilder · Mar 17, 2020

OK I had replaced just the motor unscrewed from black plastic and replaced and all windows now set and working perfectly but I think it is the sensor on b pillar that's at fault gor alarm

Datatek · Mar 17, 2020

Blobthebuilder said:
OK I had replaced just the motor unscrewed from black plastic and replaced and all windows now set and working perfectly but I think it is the sensor on b pillar that's at fault gor alarm

You mean the ultra sonic unit on the left side? should only be operational when superlocked but the sensors do fail.

P38 alarm fault

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