When I use the remote to lock the doors, the indicator lights on the doors double blink indicating a problem, and after a while the alarm sounds. After reading the manual, searching the new and old archives, and opening and closing the doors and lids including glovebox, I can't get it to return to normal operation. The remote works fine for turning on and off the immobilizer, but I am unable to lock the car without the alarm eventually going off and thus am having to leave it unlocked. The nearest dealer is two hours away and it will be several weeks before I am able to get over for them to put a scanner on it. This has happened before, but has quickly fixed itself. Does anyone have any tricks I can try or things to check so I can get this thing to return to normal operation? Thanks. Bill Z PS It is a 97 Cab.

 

Bill,

Ther eis no easy way to find out what's wrong with your alarm system unless you have the factory special tool 9540, or the "Hammer" unit.

Double flashing of the LED light means -
(1). The system was switched on by locking the door three times in rapid sucession.

(2). A fault condition was detected during the check (self-test)

(3). An alarm was triggered at least once.

Sounds like your symptoms fits #2, and 3.

There is a whole series of test you can do without having access to the special tool/computer test unit.

But it would require you to take off one of the seats off (forgot which seat the alarm module is located under), and test each test point with a volt meter while you sit in the car while turning on your remote.

Here some additional informaiton that may help you find your problem. (from factory shop manual)

The alarm is activated by:
1. Locking a door
2. Locking one of the door three times in rapid sequence.

After arming the alarm system, the operation of all actuation circuits is checked. If no fault is detected, this condition is indicated by rapid flashing of the alarm readiness lamps indicates this condition.

If a fault condition is detected, the LEDs do not flash during the check period (approx. 10 seconds)

This may be due to the following fault conditions:

1. Vehicle doors not closed
2. Vehicle doors not locked
3. Hood not closed
4. Luggage compartment lid not closed
5. Glove compartment lid not closed
6. Rear parcel shelf not closed (this must be for the CAB)
7. Radio not fitted correctly

Only those activation circuits that are not faulty are armed after the check has been terminated. A fault condition is displayed by double flahsing after the check has been terminated. If an alarm has been triggered, this is also indicated by double flashing.

Hope that will help, let us know what you find out.

 

Thanks for the help. As you suspect, I must have a fault as I have no flashing lights during the 10 sec. test period, followed by the double flashes. I guess the fault is eventually setting off the alarm, although the faulty circit is apparently not supposed to be armed. Either way, I don't know which circit is faulty and the alarm is still going off for no apparent reason. Thanks, I'll keep puzzling over it. Bill Z

 

I appreciate the suggestion. When I went out to the car at lunch, the alarm had magically fixed itself before I had even gotten into it. I drove it around, and parked it with the alarm indicating everything was working well. Now, an hour later, the alarm is going off again, and the light keeps blinking like there is a fault when I try to reset it. Usually it keeps working for months at a time before it reverts to the fault mode. What a PITA. Thanks for the vent. Bill Z

 

Does factory alarm monitor vibration? One day, on the way to the parking, i found my car's alarm went off (sound/flashing lights). The car was parked in a multi level parking structure. It was around 5:30 and lots of people were driving out of the parking. The only reason i could think that set off the alarm was all that vibration caused by drive by cars. Unlocking my door shut it off.

thx

 

Yes, vibration is what I originally attributed the random alarm to, but now I don't know. Especially as I can't get it to come out of fault mode. Thanks for the thought. Bill Z

 

As far as I know there are no vibration sensors on this systems. I remember hearing of defective switches?

 

Make sure hand-brake is all the way up. It happened to me several times where the alarm goes off when I didn't have it all the way up and at the same time the ground was not level.

Peace!
Ron

 

Thanks everyone. I'll post an update when the problem gets solved. Bill Z

 

Alarm horn is going off for no reason for me now, sometimes even when I think that I have it unarmed! This just started for me on my '96 (Immobilizer) in the middle of my road trip to Lake Arrowhead this weekend. Had to leave the car unlocked for lots of long periods.

Last time I armed it just recently, the LEDs were blinking evenly every two seconds or so. No 10 second gaps or double flashes.

Any advice would be appreciated, even just to make sure it's disarmed. It seems just opening a door may help. All of my lights work and I assume that they go off as well: trunk, glove, domes, engine. Radio plays fine. Thanks!

 

Just to briefly resurrect an old thread, if you have a fault that triggers the double-flash, and you fix the fault (lets say the engine compartment lid sensor was replaced or repaired), how do you "reset" the alarm system: just by unlocking and re-locking the car with the FOB? Or is there some other method?

The service manual says quite emphatically that once an alarm fault is tripped the system must be reset - but it never (to my tired old eyes) says how to do that. I'm either blind or thick, or ... well, I'm looking for help.

In my case, my engine lid light does its thing like my fridge - but I notice when the car is unlocked with all doors closed and overhead interior light OFF, lifting the lid doesn't turn the interior overhead light on... whereas lifting the luggage compartment lid in the same circumstance DOES turn on that overhead light. Is the lid-closed sensor not the same as the switch that turns the engine compartment light on and off??

I've combed through the service manual and parts manual and can't seem to get a clear idea about this engine compartment sensor, or how to reset the alarm system. Any help would be GREATLY appreciated. Meanwhile, I'm going to continue searching the forum posts.

Rod

 

Before you go deep on this issue make sure your at-rest battery is providing adequate voltage. Low voltage can cause all sorts of squirrely alarm issues including the door flashing in couplets.
Voltage across the battery should be at >=12.5 volts a rest after over night and > 13.5 volts in the running (charging) state. Will some reader chime in on these as the correct voltages to expect.
Andy

 

When the car is locked with the key fob it does a test of the alarm switches. If any of the alarm switch circuits are grounded (like the glove box or luggage comp lid open) the LEDs will double flash at the completion of the test. The alarm system ignores that circuit until the car is again locked with the fob. Then it starts over with the alarm test sequence.

Are you saying opening the engine lid does not turn on your interior light but the opening luggage compartment lid does? That is normal. The luggage compartment light is turned on by the alarm control unit as part of the interior lights circuit. The engine compartment light is switched directly by the engine lid latch switch.

The alarm control unit turns on the cabin interior lights when they are in the 'automatic' position and the luggage compartment light. The alarm control units uses inputs from the luggage compartment latch switch, the door open switches, the key present in the ignition switch, and the key fob, with some timing logic to control the interior lights.

See simplified diagram below. Note that the the "interior lights" ground is controlled by the alarm control unit but the power source (fuse) is different for the cabin lights and the luggage compartment light. This can cause some strange behavior if there is a problem on the power side of their circuits.

 

Um, I was pretty sure the shop service manual says the doors, the luggage lid and the engine lid all should turn on the interior light in the top centre of my windshield frame... that's why I assumed it was the culprit for my double-flashing LEDs. I'll have to go back and re-read the manual to see if I somehow mis-interpreted what it says.

So, if I had a fault, and fixed the problem, how do I "reset" the alarm module? Does it reset itself the next time I use the FOB to lock the car? I think that's what you're saying. Or do I have to pull the central alarm unit fuse in the module to reset it?

I have a set of electrical schematics for my 97 993 C2 Cab, but the person who scanned them into the manual PDF did a crap job, and large segments of the schematics are not readable, in fact not even visible. Not a big help.

Since you seem to be knowledgeable on the 97 electrics, can you explain to me how that green wire to the OEM head unit functions? It connects to a spade connector on the head mounting sleeve, but my measurements show no electrical connection to the sleeve, the head unit, or even to the large metal tab that presses up against the small piece of "tape" on the bottom of the head unit. Is there a small micro-relay embedded in the black plastic piece that the spade connector and metal tab emerge from, connecting the two when the radio is installed?

Thanks for everyone's help here, its definitely appreciated.
Rod

 

Top centre? Sorry, I didn't notice you have a cab. The alarm control unit appears to switch the ground for the "Inside Lights" the same way on the cab but there are other connections to that center light that I have not followed. Maybe you can read the attached schematic enough to follow?

Just unlock and lock the car with the fob again. If the fault has been corrected you will not see a double flash.


Attached a piece. Probably still not a big help.

The green wire is intended to operate much like the rest of the switches in the alarm system. If the factory installed radio is pulled from the car the green wire connects to electrical ground and provides an input to the alarm control unit. If you have an aftermaket radio the green wire should be disconnected and isolated (taped up?)

From a previous thread: