Trying to get the dash lights working. the one I can not get to work is the red brake indicator.

I have tried with the ABS module unplug and fuse pulled. I tried with them connected.

Today I dropped the column down and checked power at the ignition switch on the Purple white wire. Was not getting system voltage. I took the wire out of the ignition switch connector and ran a jumper to power the wire, before I went and bought and ignition switch. with 12 volts applied to the PW wire I got power at both of the PW wires at the master cylinder and the vacuum switch connector but still no power at pin 8 on the instrument panel connector and still no power from the parking brake. Fuse 18 is good

I did an internet search for the diode/resistor and could not find one. That was using the number on the wiring diagram. Where is on the truck. The manual says near the ABS module.

If we were not moving to TX next year I would not worry about it, but they have a safety inspection. When I read the inspections items it just said we look at lights on the inside.

 

Does your 4x4 indicator light up? If so leave fuse 18 and it's wiring alone. The purple/white wire doesn't get power, it goes to ground, if you ground that wire it should light the bulb assuming the bulb is good, other thing that will not make it light up is if the wires or plug on the master cylinder are wrecked or missing. Abs module not a concern atm. The resistor diode is behind the dash way up above the abs control module (brick nose style not sure where it is on the obs).

Start with basics does the bulb work? If you ground the P/W wire right at the cluster does the light turn on? How about at the master cylinder? Abs module? Start with that and don't be putting 12 volts on that wire youll get absolutely zero results.

Edit: one other thing to check especially if this is a Canadian truck is if someone unplugged the daytime running light module on the rad support below the drivers side headlight (bumper side not engine side of rad support) if thats unplugged or has broken wires your ebrake switch wont be connected to the light anymore.

Also when you start the truck does the abs light, ebrake light diesel lights prove out? Only happens when the key is moved to the start position.

 

2 wheel drive

with test light connected to ground and pin 8 on the cluster connector parking brake set ignition switch on there is no power there.

When the PW white was plugged into the the ignition switch connector was not getting voltage. That is why I pulled out of the connector and jumpered 12 vdc to the wire. That sent power to 2 of the 3 wires on the master cylinder but still nothing the cluster.

today I ohmed the PW wire at the ignition switch to the one at the cluster and it showed open

 

You need to hook your test light to 12v not ground, better to used a multimeter in this situation. Also the ignition switch on these truck have multiple switches in them, the pw wire never gets power from the switch, the switch grounds the wire not powers it.

Does your yellow abs light come on when you first turn the truck on?

Try grounding the pw wire without a test light if no go remove the cluster but leave it plugged in and try right at the cluster does it work now? If no check the bulb or swap it with another one, still no then you either dont have power going to the bulb or the foil on the cluster could be bad.

Start with that and we will find the problem.

A little ciruit theory here, there is two basic common circuit configurations used in these trucks, the first one is the switched power type, thats where the 12v power is switch to the device example being the starter, its always connected to the engine block thats connected to the negative of the battery and you give it power. The other one is what your dealing with where the device has power all the time and you give it gound, this curcuit needs the test light hooked to positive to give you readings.

Hooe that helps and isn't too confusing.

 

Right now the cluster is out and I going directly to pin 8 on connector 251 and the test light will not work there. I not real concerned about the ABS light right now. but I did test for power on pin 2 of the ABS harness and no power there.

If I am read the diagram right. The PW wire P1 at the ignition switch send power to pin 2 on the ABS module and to the master cylinder. With the ignition switch on a parking brake set, the parking brake switch grounds the circuit which send power to pin 8 of C251 at the the cluster which in turn should turn the light on. I am not getting any power at pin 8 on C251. I pulled the parking brake switch ot is doing what it is designed to do.

When I first got the truck the PO had tapped in to the LB/Bl wire one the PB and light stayed on dim. The ABS light came on a while back. I just pulled the bulb. I know there are some issues with my circuit board. I bought some 194 pig tail connectors to bypass the board. I will have to check power at pin 9 on C250.

 

Does pin 5 of c251 have power with the key on? The abs light was to check for this, thats why i asked, if you have power to pin 5 on c251 and you ground pin 8 on c251 (with a wire not the test light) it should light up as that elimates issues further downstream, if it still doesnt light up check the bulb and wiring on the insturment cluster and fix that before proceeding.

 

Yes there is power to pin 5. I put the PW wire back in the Ignition switch connector and have power there now. That must have been a loose connection. I do have power to both PW wires on the master cylinder.

 

done some more digging in the shop manual section 12-31-20 antilock testing test D7 fluid level sensor. Voltage greater than 8 v. check for open on circuit 977. so appaently I have an open somewhere.

 

using one of these I can solve the problem. I know for the parking brake side. one side to IGN power and the ground side to the PB switch. the low fluid side I am a little confused since there are two PW wires and a ground. Do I bring a wire from one of the PW wires to pwr or bring a wire from the ground side to ground on lamp?

 

Im not sure why ford did what they did but the two purple wires on the switch are connected together internally and when you have low fluild the switch will connect the black wire to the purple wires.

 

So if my new light should be wired
1 wire to a PW wire (IGN) at the master cylinder

The other wire to the PB switch and the black wire on the MC.

If I got it right apply PB makes ground light on/ low fluid completes circuit light on

Plus that take care of the old low vacuum switch delete.

 

You will need power for your light the purple/white wire doesnt have power on it (it will show 12v from the resistor/diode part but will have no current to back the voltage like a dead battery that reads fine till you put a load on it then dies) you will have to use power from pin 5 of c251 and then if you want to bypass factory wiring youll need a wire from the ebrake and one of the purple wire on the master to connect to the other side of your light.

Have you done the other checks i mentioned above? If you do your own wiring you may have the abs light on after and then youll be in the same situation again.

 

That what is was going to do. The ABS socket will not have a bulb