Cougar

Good job on the testing of the light. The trouble you are having isn't due to a short, that hopefully would blow a fuse if that was the case. The trouble is due to a bad connection to power and the resistance of that bad connection is causing the voltage to drop across the higher resistance of the bad connection. Your meter then saw what was left of the total power supply voltage that didn't get dropped across the bad connection. For example (using a normally operating circuit), it you wired in another light of the same type in series with the other light then your meter would have seen half of the voltage or around 6 volts across the last light since the two lights are the same resistance and would drop the same amount of voltage. When wired in series they have to share the total supply voltage of 12 volts. In your case though the resistance of the bad connection is a lot higher than the bulb resistance. The brake light is used for the turn signal also so if that works okay then the wiring back to the bulb should be okay. I would look the problem being with the emergency flasher switch or the flasher module possibly. If the brake light is bad also then the wire going to rear needs to be checked. I think there is a connector for the rear lights in the right rear panel but it may be the left side, not sure. The trouble may be there. Disconnect it and reconnect it to see if that changes things and if not check the voltage at that point to see if it is low there also.

If you measured those voltages at the brake switch area that means there is a bad connection in the wiring before the point you took readings at. Voltage looks okay when no load (no current flow) is applied to the circuit but when you try to pass current to the load (switch closed) the voltage drop goes across the higher resistance bad connection instead of to the load.

You should have at least a test light probe so you can check for power getting to the light at the connector for the light socket. The trouble could also be with the hazard switch or the flasher module since both circuits pass through them.

I think Fairtax4me has the right idea also. The story you are about to read is true. My son had an Outback that would blow the fuse for the brake light anytime the pedal was pressed. The short turned out to be due to the wire insulation melting in the back of one of the light sockets due to heat from the bulb. It was a good opportunity to show him how to find the trouble using an ohmmeter connected between the fuse socket and ground and watch the resistance change as light sockets were disconnected. When the resistance went higher, to a reasonable reading, you knew you had disconnected the socket with the trouble on it.

The trouble will be with the resistor block alright. It is a common issue. It will be mounted on the air duct for cooling.

The OBD2 port and the ECU tie directly to SBF-5. The relay can't cause a current draw unless the contacts are shorted together. The draw would be very significant if that was the case.

Don't you have to put a fuse in a fuse slot in order to turn OFF the AWD action, or is that with older models?

Fuse SBF 5 is the main fuse for power to the engine sensors, ecu, and to the OBD2 port, like Fairtax4me stated. If you have something plugged into that port you have found the problem. Most of the current the fuse passes can't pass until the ignition is ON and the Main Relay is turned on. If the trouble isn't on the OBD2 port then disconnect the ECU and see if the current drops down.

I could be mistaken about this but I think the 86 model used a mechanical cable for the speedo.

Good job.

I think the most likely spot for the trouble is something with the engine electrical system. A faulty power connection to the ignition system perhaps or bad contacts in the Main Relay. That relay supplies power to a lot of key engine components and it may be worth a shot to just replace it in the hope that it will solve the issue. If this was my car I would check for spark getting to the plugs as soon as the problem occurred. If spark is okay then the trouble would have to be most likely related to a fuel delivery issue. The fuel pump relay, controller, or power connection to the pump itself. Some small power indicator lights could be installed and connected to key power points of the engine systems so you could monitor them while you are driving. If power was lost to a key area the light would turn off. This kind of trouble is very frustrating for everyone involved since it can be hard to find. It can be fixed though using patients and good trouble shooting techniques.

If spark is getting to the plugs then you should check the compression. I assume the timing belts are okay.

Thanks for the update and glad you found the problem.

Like you suspected, there should be 12 volts getting to the starter solenoid. There is a bad connection somewhere between the ignition switch and the solenoid. Since the starter didn't crank well when you jumped power directly to the solenoid you either have a low battery, bad battery connections, or a bad cable due to internal wire corrosion. There should be at least 11 volts at the battery posts when the starter motor is working correctly and running.

Make sure all the engine and chassis ground connections were connected as they should be. A number of folks have had troubles due to that when making changes like you did.

Since the 12 volts seems to be having trouble I suggest you replace the Main Relay. It supplies power to the ECU and to various engine components. There could also be a connection problem going to the relay coming from the fuse panel. Both of those things are good possibilities for this trouble. The O2 sensors use the 12 volts for the heater sections only. The output voltage is generated by the sensor itself.

The flashing key and temp lights seem to indicate you have some sort of electrical problem though I'm not sure what it is unless it is with the ignition switch contacts..

Okay, disconnect the alternator connection and see what happens. If nothing changes put the connection back. It would help us if you made your statements more clearer. I can't tell from your last reply if you already tried my suggestion or you are just saying nothing starts and turns off. In your first post you seem to indicate the engine starts up and then immediately shuts down.

You might have a dirty contacts throttle position sensor.

I think you have a cold-start valve on the engine, it may have a problem.

With the key and temperature warning lights flashing this may mean something is happening to the electrical system. It may involve the alternator. I suggest you disconnect the small wire connection to the alternator which should disable it. Then start the engine and see if the other warning lights still turn on. Ignore the battery light if it turns on. If the other lights go out and the engine stays running you will have to replace the alternator.

First I suggest you check to see if there are any codes stored in the ECU that may be clues to the problem. The MAF or coolant temperature sensors may be faulty. You also might have a faulty intake manifold gasket that is allowing too much air into the intake. If that is the case spaying some WD-40 around the intake joints while the engine is running should change the idle speed.

If the light works in the manual mode then there isn't a shorting problem. The rear hatch switch most likely makes a ground connection in order to turn on the light. The switch either isn't closing to make the connection to ground or there is a wire connection problem to the switch. The switch is most likely located with the door catch. Use a test light probe to check for power getting to the switch through the room light.

First thing to do is make sure the speaker balance control and front-rear fader are set correctly. Then make sure the wire connections in the rear of the unit are making solid connection. If you have an upgraded sound system you may have an external amplifier for the speakers. If that is so, check for power getting to it.

Have the error codes checked for clues to the problem. I suspect that the security system may be causing the issue.