School Bus Fleet Magazine Forums
Home | Profile | Register | Active Topics | Members | Search | FAQ
 All Forums
 Professional Garage
 Enter Forum: Professional Garage
 Hyd. Brake problem
 New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic  

bbird66
Top Member

USA
881 Posts

Posted - 09/18/2006 :  10:08:43 AM  Show Profile  Reply with Quote
Ok..brake press light buzzer going off, Heres what I've done in order, Checked the light/hydro max switches out, work and in time, Porportion valve switch replaced, Checked tailights, both 7 inchers were rotton replaced both (clean ground) even though they worked, Switched out the monitor with another. Still same thing. Checked out flow switch, replaced that. Replaced master cylinder...Still same problem. Power steering works fine even with brake applied. I'm out of parts to throw at it. What next?

Wolf0r
Top Member

USA
2181 Posts

Posted - 09/18/2006 :  11:57:31 AM  Show Profile  Reply with Quote
What kind of vehicle bbird?

“The good thing about science is that it's true whether or not you believe in it.”
Neil deGrasse Tyson
Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 09/18/2006 :  1:28:50 PM  Show Profile  Reply with Quote
92 vintage Int./Thomas, Thinkin, short in the flow switch??

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








Go to Top of Page

Salaskie
Advanced Member

USA
453 Posts

Posted - 09/18/2006 :  2:13:23 PM  Show Profile  Send Salaskie an AOL message  Send Salaskie a Yahoo! Message  Reply with Quote
You must have the same gnome in your fleet we do :-)
The right (#2) brake light goes out. Ah, it's working now, but air pressure buzzer sounds when the tank is at 120. Then it quits buzzing and the child checkmate arms itself. Seems like 3 unrelated systems, but my hair is getting thinner.
('99 AmtranRE)
When I figure it out, I'll share :-)
Go to Top of Page

LPSMECH
Senior Member

90 Posts

Posted - 09/18/2006 :  2:27:15 PM  Show Profile  Reply with Quote
Try a 1661657c1 relay switch, I didn't see that in your list.
Good luck.
Go to Top of Page

jeepcjron
Advanced Member

USA
262 Posts

Posted - 09/18/2006 :  5:44:24 PM  Show Profile  Reply with Quote
Ignition switch ON, engine running, warning light ON and buzzer ON, backup pump OFF, immediately after engine start-up.
1. Flow switch circuit stuck open.
1. Check for flow switch continuity and check continuity of all related wires.

-
2. Relay OFF.
2. Check for power to relay. Check for malfunctioning relay. Replace relay if needed.

-
3. Bad ground for backup pump.
3. Test ground from backup pump to battery.

-
4. Monitor module malfunction.
4. Replace monitor module.

-
5. Open winding in backup pump.
5. Replace backup pump.

Ignition switch ON, engine running, warning light ON and buzzer ON, backup pump OFF, 9 to 21 seconds after brakes applied and stays ON.
1. Brake switch malfunction.
1. Replace brake switch.

-
2. Brake pedal not returning.
2. Repair cause of brake pedal not returning.

-
3. Non synchronized switches.
3. Adjust switches.

-
4. Open circuit or blown fuse to one of the two circuits to the brake switch.
4. Repair circuit or replace fuse.


its like a slinky! useless but fun to watch.
Go to Top of Page

jeepcjron
Advanced Member

USA
262 Posts

Posted - 09/18/2006 :  6:16:01 PM  Show Profile  Reply with Quote
you need to find out whats grounding the relay, try disconnecting the pres switch and the flow switch if it still sounds the module is grounding it. im doing this from memory cause our online schematics dont go back that far. i do have it in print in my tool box im sure. the later ones had that brake switch with the dual system in it. those where commonly the issue.


its like a slinky! useless but fun to watch.
Go to Top of Page

raytobe
Advanced Member

USA
293 Posts

Posted - 09/18/2006 :  8:11:01 PM  Show Profile  Visit raytobe's Homepage  Reply with Quote
Replaced many of those relay switches myself.
Go to Top of Page

slane
Active Member

18 Posts

Posted - 09/19/2006 :  02:11:00 AM  Show Profile  Reply with Quote
We had one driving us nuts also. We added a corner brace to the brake lite switch bracket, it would move enough while going down the road to set off the switches.
Go to Top of Page

jeepcjron
Advanced Member

USA
262 Posts

Posted - 09/19/2006 :  05:05:13 AM  Show Profile  Reply with Quote
here is a crappy scan of a 91 schematic

its like a slinky! useless but fun to watch.

Edited by - jeepcjron on 09/19/2006 05:07:09 AM
Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 09/19/2006 :  09:31:14 AM  Show Profile  Reply with Quote
Forgot the relay switch LPS, yeah replaced that too, funny thing was that thing would buzz every now and then when I was messin with the monitor...switched out the monitor too. Its a spare and when I catch up with the other work I'll bring it back in and start on it again. driving me nuts..Thanks guys, When its found I'll post!

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"









Edited by - bbird66 on 09/19/2006 09:36:22 AM
Go to Top of Page

Wolf0r
Top Member

USA
2181 Posts

Posted - 09/19/2006 :  09:51:32 AM  Show Profile  Reply with Quote
Dattcoron is definately an asset to this forum. Thanks for all the IC help.

“The good thing about science is that it's true whether or not you believe in it.”
Neil deGrasse Tyson
Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 09/19/2006 :  11:22:39 AM  Show Profile  Reply with Quote
He sure is, I have that schematic too Dattcoron, Been going over it.

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








Go to Top of Page

jeepcjron
Advanced Member

USA
262 Posts

Posted - 09/19/2006 :  4:23:04 PM  Show Profile  Reply with Quote
is the pump motor running? when the lights are on. if it is,
unplug the pressure and flow switch do they go off?
if its ot then unplug the module still sounding?
if so check the wire out of c cavity to ground. might be shorted to grd and turning them on

its like a slinky! useless but fun to watch.
Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 09/21/2006 :  10:49:08 AM  Show Profile  Reply with Quote
Brought the bus back in yesterday, Had some time to work on it, some more clues that lead me to think an open winding in the boost motor,

Switch on, depress brake pedal, boost motor comes on, release brake pedal (comes back all the way) motor stays on, heres a kicker turn the switch off and the motor stays running, depress brake pedal again and release the boost motor relay starts to "Chatter" and starts to get hot. Like i've said before I've changed that relay also. Unplug the relay to get the boost motor to shut off. Open winding? about the only thing I have not changed is the boost motor.

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








Go to Top of Page

misfit
New Member

USA
2 Posts

Posted - 09/21/2006 :  5:17:29 PM  Show Profile  Reply with Quote
Double check the diodes. The following is out a an old book i have. It kinda fits your last sympton.
The warning light and alarm will activate and latch ON (can only be turned off by cycling key switch off and back on). This check is to detect defective switches and circuitry.
I have used 2 test lites to verify the timing on these.
good luck MM

Edited by - misfit on 09/21/2006 5:31:15 PM
Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 09/27/2006 :  08:41:29 AM  Show Profile  Reply with Quote
Replaced the boost motor, Still same thing, Relay chatters so I'm checking the diodes. About the only thing left.

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








Go to Top of Page

Wolf0r
Top Member

USA
2181 Posts

Posted - 09/28/2006 :  06:58:46 AM  Show Profile  Reply with Quote
You might check any power/grounds that share this circut.

“The good thing about science is that it's true whether or not you believe in it.”
Neil deGrasse Tyson
Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 09/28/2006 :  8:40:31 PM  Show Profile  Reply with Quote
I took the cover off of the junction block (Drivers side) and found a mouse nest in there, Some insulation chewed off but not enough to short out anything. I have narrowed down the circut but I'll be damned if I can find it, I'm sure its behind the dash somewhere. The relay sure gets pretty darned warm after awhile chattering. I'm throwing in the towel and taking it to the dealer Friday. At least I'll have saved them a lot of time. Jesssh this thing has drove me nuts... I'll post what they find.

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 10/09/2006 :  1:26:01 PM  Show Profile  Reply with Quote
Here's the update and repair taken from the invoice the tech printed out. What makes me mad is that I should have pulled more fuses!

"No power at wire #90 U for Ign feed had to take dash apart to trace wireing, no fuse in fuse box for B1, So trace D back found fuse for wire listed under "fuel" (Fuel socket was being used for B1!) Fuse was blown, replaced 20 amp fuse, System working properly".

Took him 3 and a half hrs to trace it.


Had this happen before a long time ago where B1 supply was the reverse lights fuse!!. Like I said wish I would have checked more fueses!!

Did not get to talk to the tech, I dont know why the fuse blowed, I do know the day this happend it was raining and water was seeping in around the cowl so that may have done it. Wet somewhere behind the fuse panel.

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








Go to Top of Page

Thomasbus24
Administrator

USA
4515 Posts

Posted - 10/10/2006 :  03:15:07 AM  Show Profile  Reply with Quote
Thanks for the update...I'd been wonder what, if anything they had found.

Now...let's all start buying air brakes!
Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 12/14/2006 :  07:13:36 AM  Show Profile  Reply with Quote
Well...this thing has reared again, Blowed another fuse to start with so I put a 30 amp in from a 25. Lasted awhile then the 30 amp Ing. fuse blowed. Short is somewhere between the systems, Tore the doghouse off, dash out, fuse block out, Switched out the key switch, Attached short finder moved, yanked wires, problem goes away...Then comes back after a week randomly blowing either the B+ feed wire or Ing fuse. driving me nuts, Short finder breaker does not stay on long enough to get a good reading. About ready to put a 4 gauge jumper wire in and stand by with a fire ex. Gonna need therapy before long! lol. Going to tear into it today..

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 12/14/2006 :  09:42:49 AM  Show Profile  Reply with Quote
As usuall soon as I start messing with it it goes away, Hydromax motor will run with key off after pressing on brake pedal, Start to pull fuses...all chassis fuses pulled, still runs, Rap on the boost relay and it will quit. Sometimes chatters..

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








Go to Top of Page

Thomasbus24
Administrator

USA
4515 Posts

Posted - 12/14/2006 :  2:15:57 PM  Show Profile  Reply with Quote
May I suggest an exorcism?
Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 12/15/2006 :  05:00:41 AM  Show Profile  Reply with Quote
Lol!....need one for myself pretty soon! Calling a district man from Int. that lives in the area. Maybe I'm barking up the wrong tree...

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








Go to Top of Page

screwy
New Member

United States
3 Posts

Posted - 01/03/2007 :  10:14:56 AM  Show Profile  Visit screwy's Homepage  Reply with Quote
Is the buzzer one that also works for the oil pressure/water temp? Try replacing with a known good one. Had them shorting out inside.

Also, all brake lights for proper bulbs. Found wrong bulbs (single in a dual, dual in a single, etc.).
Go to Top of Page

bbird66
Top Member

USA
881 Posts

Posted - 01/04/2007 :  12:11:10 PM  Show Profile  Reply with Quote
Done that too, There is a short somewhere behind the dash, I've had the dash out and with my short finder it goes crazy, but its such a hot short the stupid breaker gets hot real quick and pops out thereby I dont have much "Crazy needle" time. I sidelined the bus and when I get time I'll go back at it again. Dist man has not called me back yet either...

Were gonna miss you "Brent"..Good luck in "Heidi land"

"I know you miss the Wainwrights Bobby, but they were weak and stupid people...and that's why we have wolves and other large predators" .. The Far Side

"On a two hour delay when will my child be picked up??"








Go to Top of Page
  Previous Topic Topic Next Topic  
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
 


School Bus Fleet Magazine Forums © 2017 School Bus Fleet Magazine Go To Top Of Page
This page was generated in 0.17 seconds. Snitz Forums 2000