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Testing the MFS

wesley410

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So i found this thread on how to replace the thing
http://www.explorerforum.com/forums/showthread.php?t=137784&highlight=multi+function

But I want to know how can I check if it is actually the problem besides the obvious: everything not working,
*Please explain like I am five* pictures would be nice

******eta******
the brake lights, turn signals, and hazards do not work
running lights (including running brake lights, dual filament), high beams, wipers [didnt check delay] work
************

Can i grab a piece of wire and complete the circuit for any two colored wires?
so i can see if the brakes, or hazards or turn signals work....

ive got the covers on the steering column off, i have a multimeter if needed, but no test light.

my "smart brother" decided to tow a car, and used the frame as a point to hook a steel cable he was using for towing....tore up the wiring harness...of course when i pointed out the lights werent working...he looked and the problem was as he suspected...dumb***

so now im stuck footing the damned bill if i want it working anytime soon
wires repaired to the best of my ability...most had the insulation chewed off...i put electrical tape over it.
a couple need to be soldered...rather re-soldered cuz im crappy at it..but there is continuity
 
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rb142

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You need to get a good wiring diagram showing the wires and pins at the MFS connectors. Search around here -- there are some places you can get the diagrams online. Then you could figure out how to run some tests by appropriately powering/grounding/jumpering wires to test functions in place of the switch. But be sure you know the right test to do before you start poking around. Putting power to something that can't take it, for instance, could potentially do harm. We can't suggest specific tests without studying the diagrams.

Because everything you mentioned is in the back end, and you described the damage to the wire harness, I would guess that your problems are in that harness, not the switch.
 
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wesley410

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wiring diagram

i think this is what you mean...but this is where i need it explained to me like i am five...i have no clue how to read it.

I will check my solder joints again...i admit im not the best at making them. But i think there should be a good connection.

I think that if there was enough for it to blow out the fuses, it could have done the MFS too.

Diagram_turn_stop_hazard.jpg
 
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rb142

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OK, here's an overview. You have power supply at the top of the diagram, and it flows down through the circuits to grounds at the bottom of the diagram. You have battery voltage coming off the fuses at the top (no lower voltage stuff here). The small letters are the colors of the wires: e.g. LB is light blue, LG/W is light green with a white stripe, etc. The small numbers are the connector pin number. With these, you should be able to locate the wires in the harness/connector. Numbers starting with Cxxx are connector numbers, and numbers starting with Sxxx are splice numbers, but you don't need those.

This is a pretty simple circuit with straight-up switches putting battery voltage on the switch outputs, flowing down through the bulbs to ground. Jumper battery voltage onto the light green with orange stripe wire and the left rear should light up. Jumper it to the orange with light blue wire and the right rear should light up. And so on. If you step on the brake you should have battery voltage on the light green wire. The flashers turn steady battery voltage into a blinking on/off voltage signal supplying the switch. If you connect an incandescent test light (or some other bulb designed for 12V) to the light blue or the white with red wire, you should get the light blinking. Do not ground these wires directly -- there needs to be some load there or you could burn up the flashers. You didn't say anything about the wipers or high beams. Those are on another diagram, but the tests would work the same way. That will prove out the wiring all the way to the tail lights. It goes without saying that you should check ALL the fuses and verify you have battery voltage coming in before anything else. The flashers are hiding under the dash, so check the voltage at the MFS where it is easier to reach.
 
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wesley410

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The small letters are the colors of the wires: e.g. LB is light blue, LG/W is light green with a white stripe, etc. The small numbers are the connector pin number.

what colors are indicated by p/o h and r/w h (this seems like red/white) This is at the top of the diagram, i assume for incoming power. p/oh is under hot in run and r/wh is under hot at all times.


Jumper battery voltage onto the light green with orange stripe wire and the left rear should light up.

this should occur when i press the brake or instantly...also battery voltage is from what color wire?

If you step on the brake you should have battery voltage on the light green wire.

i guess this answers my question immediately above...it will light up when i press the brake?

If you connect an incandescent test light (or some other bulb designed for 12V) to the light blue or the white with red wire, you should get the light blinking. Do not ground these wires directly -- there needs to be some load there or you could burn up the flashers.

i bought a light tester at walmart. S I check the red wire or light blue wire for power and my light should blink according to the instructions.

what do you mean by not grounding these directly?


You didn't say anything about the wipers or high beams. Those are on another diagram, but the tests would work the same way. That will prove out the wiring all the way to the tail lights. It goes without saying that you should check ALL the fuses and verify you have battery voltage coming in before anything else. The flashers are hiding under the dash, so check the voltage at the MFS where it is easier to reach.

wipers, high beams, running lights work (didnt check reverse lights). Just no turn signals, either outside with the brake lights or on the instrument cluster, no hazards in either places.


Im hoping to work on this tomorrow. with plenty of day light. Ill take some more wire and check my solder joints. For wire gauge, the number idicated on my wire striper when i strip the wire is the gauage i will need, correct?
 
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rb142

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what colors are indicated by p/o h and r/w h (this seems like red/white) This is at the top of the diagram, i assume for incoming power. p/oh is under hot in run and r/wh is under hot at all times.

p/o is probably pink with orange stripe. r/w is red with white stripe. I'm not sure about the h -- that probably indicates hot.

this should occur when i press the brake or instantly...also battery voltage is from what color wire?

instantly

i guess this answers my question immediately above...it will light up when i press the brake?

No. The light green wire coming out of the stop light switch going into the MFS. Don't confuse that with LG/O or another stripe combination.

i bought a light tester at walmart. S I check the red wire or light blue wire for power and my light should blink according to the instructions.

what do you mean by not grounding these directly?

If you connect a ground wire directly to these points, you will probably blow up the flashers. There has to be some resistance in the circuit to limit the current flow. Normally this is done by the light bulb. A regular test light usually serves the same purpose. Some of the LED test lights, however, do not have enough resistance.

wipers, high beams, running lights work (didnt check reverse lights). Just no turn signals, either outside with the brake lights or on the instrument cluster, no hazards in either places.


Im hoping to work on this tomorrow. with plenty of day light. Ill take some more wire and check my solder joints. For wire gauge, the number idicated on my wire striper when i strip the wire is the gauage i will need, correct?

Do the front turn signals work? It's always good to look for the common link when you have multiple failures. If the front signals work, but not the back or the instrument cluster, look at the G200 common ground point or one of the splices on the ground side that is common to those. If the front turn signals also don't work, the most likely common element there is the MFS. Narrow it down. Pick one path (the easiest one) and follow it until you find the problem. Chances are that will fix the other problems too.

Yes, the numbers on the stripper are the wire gauges. If you replace sections, use the same gauge you took out.
 
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wesley410

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Front turn signals do not work either.


As an update, I have not had a chance to work on this.
 
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Denyka C Powell

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awwww, i wish this thread wasn't so old. This is heading the direction of where MY brake lights not workings' answer might be.:(
 
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