Explorer OBD II harness question

[Green_Bastard]

Hey guys,
so I'm about done with my full restore that includes the Explorer EFI conversion as well as LED lights on all corners. I noticed that after hooking everything up my taillights are on. After tracking through the harness, I found that the power is coming from pin 4 on the C115 plug from the Explorer harness. This is the red/green wire that goes to the brake light switch and should be hot when pressing the brakes. I checked the voltage and it looks to be between 5 and 6 volts coming through it. If I swap out the LEDs for traditional bulbs, its not enough voltage to light them up. I've doublechecked to verify its not shoring across with another power source.

My question is, should there be any voltage on that wire coming from the computer? Can someone check theirs to see if anything voltage is coming through?

 

[EPB72]

In the factory harness (explorer ) brake light switch pin 1 ground ,,, pin2. Red light green is brake pedal position in put to ecm… pin3 brown. Power in hot all time …. Pin4 light green is the output for your stop lamps … pin5 light green red power hot all time ,,,, pin 2 is only wire connected to pcm with should be at pin 92 of the pcm. Connector … But not knowing your setup need more info/ pictures maybe wiring a little mixed up???

 

[Green_Bastard]

In the factory harness (explorer ) brake light switch pin 1 ground ,,, pin2. Red light green is brake pedal position in put to ecm… pin3 brown. Power in hot all time …. Pin4 light green is the output for your stop lamps … pin5 light green red power hot all time ,,,, pin 2 is only wire connected to pcm with should be at pin 92 of the pcm. Connector … But not knowing your setup need more info/ pictures maybe wiring a little mixed up???

I'm not sure what connecter you're referring to. I'm looking at the C115 plug. The first five wires are as follows.

pin 1 - red/green - power to coils
pin 2 - brown/yellow - tach signal
pin 3 - pink (twisted pair) - OBDII port
pin 4 - red/green (like coil wire but thinner) brake like switch - hot when on brakes - used for decel and torque converter lockup
pin 5 - green/yellow - fuel pump relay

The harness is from a 98 Explorer and I'm running the 4R70W as well.
Specifically I'm looking at the wire on pin 4. This should be hot when on the brakes, however I've noticed that when not pressing the brakes, and even when disconnecting this wire from the brakes for isolation, it has approximately 5 volts running through it. I need to know if this is normal. I've doublechecked the wiring and connections and it's all correct.

 

[EPB72]

The pin locations I was referring to was the factory explorer brake light switch connector, but I looked up for a 2000 so 98 could be different but I don't think so,,,and I'm guessing your using the stock bronco brake light switch ....

The wire red/ grn. at pin 4 you are referring to is not for brake lights it's for brake pedal position input to the pcm..The pcm sends out 5 volt reference on that wire ...
The stock explorer brake switch has 2 switches in one unit .one for the above circuit and one for the brake lights..

I can check tomarrow if 98 is the same as a 2000,,,,and I'm not sure if people are even using that input or they just leave it disconnected??I run Manual trans so maybe some one else can chime in...

 

[Green_Bastard]

The pin locations I was referring to was the factory explorer brake light switch connector, but I looked up for a 2000 so 98 could be different but I don't think so,,,and I'm guessing your using the stock bronco brake light switch ....

The wire red/ grn. at pin 4 you are referring to is not for brake lights it's for brake pedal position input to the pcm..The pcm sends out 5 volt reference on that wire ...
The stock explorer brake switch has 2 switches in one unit .one for the above circuit and one for the brake lights..

I can check tomarrow if 98 is the same as a 2000,,,,and I'm not sure if people are even using that input or they just leave it disconnected??I run Manual trans so maybe some one else can chime in...

Ok, thanks for clarifying. What you were describing makes a little more sense to me now. I was able to get ahold of Garry this evening and he did verify I have it hooked up right for proper TC lockup but some of the computers put out a little bit of voltage on that line. I was able to fix this by adding in a diode to keep voltage from flowing through this line out to the brake lights.