85 E350 random brake dash light coming on
- Thread starter Cubey
- Start date
Tuna can with wires and one vacuum line. F has it on the passenger wheel well. You'll need to follow the vacuum line to find it in your E.
Brake proportioning valve should have an idiot light switch in it that tells you right after the pedal goes to the floor that the pedal just went to the floor.
Brake proportioning valve should have an idiot light switch in it that tells you right after the pedal goes to the floor that the pedal just went to the floor.
I thought the coffee can was just a reservior and the sensor was separate. At least, that's how it looks on my F250. Harder to track stuff in the cramped E350.
Pretty sure I have the can unhooked and have for a year. I put caps on the tree, leaving cruise and the can unhooked.
The light is coming on while driving with no brakes being applied.
That is the vacuum reservoir.
https://www.oilburners.net/threads/6-9-vacuum-related-questions.35987/
Second pic between the ball shaped reservoir and the horn
https://www.oilburners.net/threads/6-9-vacuum-related-questions.35987/
Second pic between the ball shaped reservoir and the horn
Yes they are a metal coffee can. Same one I have. That's not what I'm pointing you towards; just a clear pic of the tuna can. Look at the other component in the pic I linked so you have a general idea what it looks like.
You can disconnect the e brake switch, etc and see if the light still misbehaves.
You can disconnect the e brake switch, etc and see if the light still misbehaves.
Ah, yeah. My F250 has the coffee + tuna.
I will eyeball the parking brake switch. The equalizer bracket fell off after i went to press the pedal and it went limp. I didn't think to go under to investigate, I just thought a cable broke. The bracket fell off then or later when driving. I have the pedal zip tied upward, since it wants to drop without the cable linkage hooked up. It's been that way almost a year though, and the brake warning light just started recently.
Guess what... my E350 actually has the coffee can AND the ball. Weird, eh? The coffee can is on the passenger side and the ball is on the driver side. I guess that's what it is anyway. Very odd. Both seem tied to the cruise servo.
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Coffee can is reservoir for cruise control vac as stated
Check this video I just recorded. Two hoses attach to the cruise servo. One going to the coffee can, one going to the ball. Maybe it's a van only thing?
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Mine was in a LOT worse shape than that. Just a complete vacuum leak. Might as well have not even been on there.
I built my own. Here it is:
What is referred to as the tuna can is the vacuum switch.
Here it is, from the other post that was referenced earlier...
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Here is what it looks like on my rig:
If it loses vacuum, it switches on the light on the dash. Mine was doing the same as yours. No rhyme or reason to when it would light up. I just disconnected the wiring connector. Problem solved, because the brakes work just fine. Faulty switch.
If you want to keep the switch... I found it impossible to find the factor replacement switch. But there is a thread here that shows how to replace with a different switch. I ordered the switch, and will replace that in due time.
Here is that thread:
https://www.oilburners.net/threads/low-vacuum-warning-switch-tuna-can.86790/#post-1041917
In your video...
See that "manifold" hanging above your cruise control?
The one with all the vacuum lines on it.
Trace each of those vacuum lines. One of them will lead you to the tuna can.
No idea why you have both a ball and a can.
See that "manifold" hanging above your cruise control?
The one with all the vacuum lines on it.
Trace each of those vacuum lines. One of them will lead you to the tuna can.
No idea why you have both a ball and a can.
Yep. I have cruise and... something else.. forgot what now... unhooked. You can see the vinyl caps on the manifold. I did that when the old failing vac pump was on there to reduce the load as much as possible. I think vent was unhooked but i put it back after I replaced the pump.
Let's see.. this is what is connnected
Supply from vac pump
Throttle VRV
Vents
Brake booster
Two lines are unhooked. Cruise and... tuna can?
If they are unhooked and just laying about, yeah, trace those as well.
All I can say is that the tuna can has to be at the end of a vacuum line, and two wires.
If you don't find it at the end of any vacuum line, then find out where the wires are, at the other end. Find those and trace them to the switch.
If you go through all that, and just find loose wires and no vacuum line... then your switch is missing. And probably not causing the dash brake light problem. (Unless those wires are somehow making contact with each other, or a point of grounding somewhere.)
All I can say is that the tuna can has to be at the end of a vacuum line, and two wires.
If you don't find it at the end of any vacuum line, then find out where the wires are, at the other end. Find those and trace them to the switch.
If you go through all that, and just find loose wires and no vacuum line... then your switch is missing. And probably not causing the dash brake light problem. (Unless those wires are somehow making contact with each other, or a point of grounding somewhere.)
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