Re: Peculiar Electrical Bug
From info on a '94, there is a 15 amp fuse, fuse "E" underhood. This fuse feeds six items:
Cruise control actuator
HO2 Sensor (heater side of O2 sensor)
DRL (Daytime Running Lights module, your bio says Canada)
Auto Trans (just to power back-up lights through part of the switch on the trans.)
One ABS Power Relay (in the Trailering Relay Box)
4WABS module power
Speedo loss makes sense, as rear diff speed sensor feeds 4WABS module info, 4WABS sends it on to PSOM (speedo module), so loss of ABS module power kills that. 4WABS fail light come on if module dead. Trans. error light I theorize may be turned on by EEC since it sees trans turning, but no output at rear diff.
According to color code, all of the supply wires downstream from Fuse "E" are Purple w/ Orange Tracer, all except the 4WABS Power Relay.
First I would check any modifications... a stereo, lights, etc? added to this vehicle? Have seen people just look for any wire with switched 12 volts to tap into! DUH! Pull fuse and see if they die also.
If okay, the O2 sensor wiring down by it is worth a look. The color code is for the harness, the sensor wires themselves may have their own code. The ground for the O2 heater is Black. Wires down there bare or melted/burned, ?
Could unplug Cruise actuator under hood at the unit, and run that way to see if it repeats.
Can you unplug the DRL module in front of the driver side radiator area, and run without DRL for a while?
The back-up light you would think would only operate in reverse, lowering probability of it being the problem (unless it pops after putting it into reverse!)
If you can disconnect some of this stuff only one at a time, and see if the fuse problem goes away, that will narrow it down. But I wouldn't junk something expensive unless you can really prove that is the problem.
Post back if you get any more info, or have questions, we all can learn something.