Dash brake light indicator

[foredeckguy]

The dash brake light is supposed to come on for a few seconds when the key is first turned on to show the bulb is working and then go out to indicate the brake system is ok (fluid level for sure), all of this without the parking brake set. My bulb is good, the parking brake will turn it on, but I don't get the on/off cycle when first turning the key. Circuit diagrams in my manual and found on line do not include the master cylinder low level switch and whatever it is attached to. Anyone figure out what the 3 wires to switch should be seeing? Is there a control module for this?
This is the last item I failed inspection for and I only have 6 more days to fix it before the temporary tags expire! Thanks to all on the forum who have shared a wealth of information. I fixed the door ajar light, 2 inside door handles and latches, dash light and indicator bulbs, EGR fault, found keypad code, replaced shocks,rear bumper and upper control arms.

 

[foredeckguy]

Found the fluid level switch in the Haynes book. Shorting the purple/white and black wires at the master cylinder makes the dash brake light come on. So the warning circuit is operational, it's just the test sequence at start-up that's not working. So I guess replacement DRL module is next. Can anyone confirm this?

 

[foredeckguy]

So where is the DRL module on a '96. All the internet and even the manual the salvage yard mechanic has said behind the drivers side headlight. It's not there. I've been through my truck and one at the salvage yard and it's nowhere in that corner of the vehicle. Anyone actually find it on 96??

 

[firepop5]

My wiring diagram shows the third wire at the master cylinder to be tan/light green. This wire should provide ground to turn the lamp on when the key is in the start position. See if this wire provides ground when turning the key. Are you sure your car has daytime running lights?

 

[foredeckguy]

No I'm not sure about DRL but the only diagram I have shows it in the circuit from the fluid switch to the dash indicator. Does your diagram show the relay or module that is supplying the ground signal and do you know where it is located? I don't care about daytime running lights but this is the last item I need to fix to complete my inspection and get real tags on the XLT. Thanks for your help.

 

[firepop5]

According to my diagram the brake light receives power whenever the ignition is in start or run, through fuse 11. It receives ground from one of 3 paths.
The first is through the tan/light green wire when the ignition is in the start position. Ground travels through the tan/LG wire to the master cylinder and back to the light through the purple/white wire. (the tan/LG wire is connected to the purple/wh at the master cylinder) The black wire at the master cylinder is a direct ground.
The second is through the purple/white wire when the brake fluid is low. When fluid is low, ground passes from the black wire through the switch in the master cyl. and back to the light through the purple/ wh.
The third is through the light green/red wire from the parking brake switch when it is depressed. This third path to ground passes through the DRL module if your car has DRLs. If no DRLs, ground goes directly from from the parking brake switch to the light. It receives it's ground right at the parking brake pedal. You said the light turns on when you apply the parking brake, so DRL or not, this path to ground seems fine. To me it sounds like the ground is not received through the tan/light green wire when the ignition is in the start position. You might have a problem with the ignition switch itself or it's wiring.
The tan/light green wire should be at the master cylinder. It runs from here to the ignition switch. See if it provides ground when the ignition is in the start position.

 

[foredeckguy]

I found a web site with the full diagram (60 some pages) and found exactly what you describe. I checked the ground was being applied to the connector at the master cylinder by the ignition switch but the contacts were in desperate need of cleaning. Once done, works like it should. I wasted a lot of time looking for a DRL that isn't there. Oh, the brake light to test the fluid level switch only comes on in the start position, which frees it up in the run position to come on for a brake or low level signal. Thanks for your reply, I was starting to get really frustrated trying to get this straight. Haynes manual leaves a lot to be desired for electrical repairs.

 

[RHM]

I found a web site with the full diagram (60 some pages)

Can you share the website? or is that not allowed on this forum? (newbie)

 

[alohamonte]

My brake light comes on for a few seconds at start up, but when the e-brake is applied it does not illuminate. Bad sensor?

 

[1998Exp]

My brake light comes on for a few seconds at start up, but when the e-brake is applied it does not illuminate. Bad sensor?

If your e-brake switch is like mine, it's just a very simple device with an exposed contact, which catches dirt and oxidizes easily. Take it off and clean with sand paper or emery cloth.
As for the light turning on at start-up, there is a possible answer already in this thread. Is your fluid level OK?