When snakes were hissing under the dash, and my brake booster was bad, these 2 lights would fade on slowly. I've replaced my booster and master cylinder and now the 2 lights are ALWAYS on. Vacuum seems fine, as the truck stops GREAT now. The vacuum line going to the pressure sensor on the fender looks very new and supple. No cracks.

Any other reason's they would be on other than low vacuum?

 

I'll check better in a while, but I believe that the FSM says that when it stays on it has a stored fault code. Ground the black wire like the sticky says and count all flashes...Mark

 

bleed the breaks when i put the line lock on it did this too

 

Here is what the FSM has to say about it

http://www.dieselbombers.com/1st-gen...iagnostic.html

 

Check for air in the system. I had a shop bleed my brakes,and the lights are gone.

 

"The vacuum seems fine" is no way to tell... I would recommend checking the vacuum and see if it meets the minimum for the vacuum sensor to trigger the light. 8hg. IIRC is the minimum. Someone correct me if I am wrong please...

 

Thanks guys. I never knew they had this way of seeingcodes on the non ic trucks.

There is still a little air in the lines, I can feel it when I pump once. Hopefully it's that.

I'm running just one vacuum pod for now with the bottom one blanked off. However, with it just hanging there (so not working) AND the booster leak, the 2 lights would fade slowly on and off depending on RPM. I'm PRETTY confident Vacuum is 8"Hg or better, but I'll check anyway. I'm putting money on a little more air (hurried bleed) in the RWAL unit.

Also, if I understand correct you must disconnect the battery for 30+ seconds to clear a code anyway or ground something.... I'll do that too.

Thanks for all the great tips guys, and the pdf's RSWORDS.

 

8in hg is the minimum vacuum you should see. a good vacuum is about 18in hg. i have 20in hg on mine even after removing the lower diaphragm.

 

i pulled the bulbs and now mine are off

 

I just removed that box from behind the glove compartment.

 

Ha... it's because of these two lights that I didn't realize my parking brake was on during my dyno run!!

It's nice also cause it will tell if your fluid level is getting low I think.

 

idk what fluids it would tell you about but yea ive toasted the ole back brakes a few times with the ebrake on so i understand where your comin from.