1997 Saab 9000 weird ABS problems: 1. Occasionally, the ABS instrument panel light will come on without the brakes being applied and the ABS system being activated. 2. Sometimes, even though the brakes are not being applied,the ABS system will kick in but the instrument panel light will remain off.

I would say you have a problem with your anti lock brake system WSS sensors issue ABS . Or vss sensor
You see if the abs has a sensor problem and you don't fix it for a long time the bulb burns out then the brake light comes on as a back up for the system .
Try replacing the amber bulb in the instrument cluster panel; for the abs look at what happens This is not a simple problem .

Check hose going to power booster for leaks.

Cheers guys but it's not a key fob, it's a weird torpedo shaped device you press directly onto a small metal disc beneath the immobiliser light. It's an old L reg Saab 9000. Any ideas?

Maybe the anti lock brake ecu is bad or the sensors need to be replaced on the appropriate wheel as indicated by fault codes for the ABS system.

Fault codes were not provided on the original 1989 model of the Saab 9000, but the 1990 to 1991 model ecu can be installed and fault codes read from the AntiLock warning lIght flashing codes.

Check wiring to ensure there are no opens to the module from the ABS Wheel Speed Sensors.

Maybe check that the wheel speed sensor is picking up a sinusoidal wave of AC electricity when the wheel is spun as seen on an oscilloscope function of a multimeter. This would isolate the problem to wiring or the ECU being at fault.

If this car is an Aero, access the lights from inside the hatch. Pull back the felt/covering and
you'll see the light assembly. Take it from there.

U NEED A SPECIAL SCANNER TO GET ABS CODES, A GENERIC SCANNER WILL NOT WORK.

yeah you mostlikey have a abs pressure switch problem. which helps in the power assist , and or the seal in the brake booster is going bad

Remove the instrument panel form the dash. Pull the back off and resolder resistor R13 on the back circuit board. This is a fairly delicate job and requires a fine pointed soldering iron. This fixed the Tach, Odometer readout, and fuel guage but not the speedometer in my 85 900 s.

Any ideas on the speedometer?

I have this same problem

on most dodges there is abs its the rear drums u may wont to get them check to see if they have to be replaced. As for ur parking brake if the light is on u may have to replace the rear drum and pads. I had the same problem with my 97 dodge 1500. also try bleeding the system this could also help