Pacbrake and warning light promlem

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stuplich@ymail.com
Posts: 1146
Joined: Mon Oct 28, 2019 8:51 am

Pacbrake and warning light promlem

Post by stuplich@ymail.com »

What might cause the "service brake warning light" on the dash to come on any time that the Pacbrake ON/OFF switch in the console to the left of the driver is in the ON position?
(When the switch ON the Pacbrake works normally.... but the "warning light on the dash" should NOT illuminate)
Mel
'96 Sahara 3530, mine since '01
250 hp 3126 Cat, MD3060 Allison
buddaman
Posts: 10
Joined: Tue Oct 29, 2019 10:39 am

Re: Pacbrake and warning light promlem

Post by buddaman »

I think there all possessed ,My 2001 zanzibar brake service lite and alarm go off occasionally when i'm maneuvering to park.Had brakes checked and no problems. Good luck
steve 2001 safari zanzibar
buddaman 2001 zanzibar
Robert K
Posts: 105
Joined: Mon Oct 28, 2019 2:27 am

Re: Pacbrake and warning light promlem

Post by Robert K »

I would go with the old stand by ,its a ground wire.
I can't think of any other connection between the two.
Bob
96 Serengeti 37'
3126 Cat
6 speed Allison
2011 jeep wrangler towd
TDJohn
Posts: 552
Joined: Sun Oct 27, 2019 11:34 pm

Re: Pacbrake and warning light promlem

Post by TDJohn »

buddaman wrote: Thu Nov 14, 2019 2:15 pm I think there all possessed ,My 2001 zanzibar brake service lite and alarm go off occasionally when i'm maneuvering to park.Had brakes checked and no problems. Good luck
steve 2001 safari zanzibar
Steve,

No exorcist is needed. :mrgreen: The reason that the alarm chirps or goes off momentarily is because when you are maneuvering to park, you are at low rpm and have a high hydraulic load. You are using your brakes and loading your power steering, this causes the pressure to momentarily and intermittently drop.
BTW, when that alarm goes on, you should also hear and feel the electric back up motor for the hydroboost kick on. As a routine check, with the ignition off, firmly step on the brake pedal. The alarm should sound and at the same time you should hear the back up motor kick in and a second later, you should feel the pedal drop as you gain boost assist.
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.
TDJohn
Posts: 552
Joined: Sun Oct 27, 2019 11:34 pm

Re: Pacbrake and warning light promlem

Post by TDJohn »

stuplich@ymail.com wrote: Thu Nov 14, 2019 1:56 pm What might cause the "service brake warning light" on the dash to come on any time that the Pacbrake ON/OFF switch in the console to the left of the driver is in the ON position?
(When the switch ON the Pacbrake works normally.... but the "warning light on the dash" should NOT illuminate)
Mel,

This is just a guess, but it might be that some wires rubbed through and are shorting to the brake alarm system, or something is causing the pac brake power to back feed via the brake switch.
I have heard that some people would rewire their brake light or just third brake light to light up when the exhaust brake is activated. If you have that setup maybe some how it is back feeding. Maybe there is some kind of fault that the CAT ECM or the Allison TCM is sensing?

I don't think Jim Exler signed onto this group, so I would suggest that you either email him directly or post it on the old sight so he could see it. He would be the likely one who could help you out with this odd ball issue.

BTW, this should have been posted in the Technical discussion. Maybe one of the moderators can move it over there, where it belongs...
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.
stuplich@ymail.com
Posts: 1146
Joined: Mon Oct 28, 2019 8:51 am

Re: Pacbrake and warning light promlem

Post by stuplich@ymail.com »

TDJohn wrote: Fri Nov 15, 2019 2:31 am
stuplich@ymail.com wrote: Thu Nov 14, 2019 1:56 pm What might cause the "service brake warning light" on the dash to come on any time that the Pacbrake ON/OFF switch in the console to the left of the driver is in the ON position?
(When the switch ON the Pacbrake works normally.... but the "warning light on the dash" should NOT illuminate)
Mel,
This is just a guess, but it might be that some wires rubbed through and are shorting to the brake alarm system, or something is causing the pac brake power to back feed via the brake switch.
I have heard that some people would rewire their brake light or just third brake light to light up when the exhaust brake is activated. If you have that setup maybe some how it is back feeding. Maybe there is some kind of fault that the CAT ECM or the Allison TCM is sensing.

I don't think Jim Exler signed onto this group, so I would suggest that you either email him directly or post it on the old sight so he could see it. He would be the likely one who could help you out with this odd ball issue.

Image
Thanks John
BTW I'm lucky that I'm able be able to post here at all, (navigating to the correct discussion is above my pay grade).
Sorry, but I'm sure I'll figure it out in time.
Mel
'96 Sahara 3530, mine since '01
250 hp 3126 Cat, MD3060 Allison
bdub
Posts: 23
Joined: Wed Oct 23, 2019 6:48 pm

Re: Pacbrake and warning light promlem

Post by bdub »

This will help. Hit the "Quick Links" icon right below the board title on the left side. Then choose "Active Topics" search.php?search_id=active_topics. Topics starting with red flags are ones that you have not read yet. Check it out.
bdub
stuplich@ymail.com wrote: Fri Nov 15, 2019 9:18 am BTW I'm lucky that I'm able be able to post here at all, (navigating to the correct discussion is above my pay grade).
Sorry, but I'm sure I'll figure it out in time.
Billy Massey
40' 1998 Serengeti, 3621b Cat 300hp
2015 Willys
Brownwood, in the Heart of Texas
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stuplich@ymail.com
Posts: 1146
Joined: Mon Oct 28, 2019 8:51 am

Re: Pacbrake and warning light promlem

Post by stuplich@ymail.com »

bdub wrote: Fri Nov 15, 2019 11:33 am This will help. Hit the "Quick Links" icon right below the board title on the left side. Then choose "Active Topics" search.php?search_id=active_topics. Topics starting with red flags are ones that you have not read yet. Check it out.
bdub
Thanks Bill ..that IS helpful
Mel
'96 Sahara 3530, mine since '01
250 hp 3126 Cat, MD3060 Allison
bdub
Posts: 23
Joined: Wed Oct 23, 2019 6:48 pm

Re: Pacbrake and warning light promlem

Post by bdub »

You're welcome. I'm really glad to contribute SOMETHING! So far, I'm all into asking questions! :-)
Billy Massey
40' 1998 Serengeti, 3621b Cat 300hp
2015 Willys
Brownwood, in the Heart of Texas
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RSBILLEDWARDS
Posts: 39
Joined: Sun Nov 03, 2019 8:10 am

Re: Pacbrake and warning light promlem

Post by RSBILLEDWARDS »

Know that I have not driven the Z since I bought the Panther 5 some years back. If memory serves me correctly that little light was on to say that the PAC Brake was in an "active mode" ie on. I did not view it as a warning light. I was is very much like the little green light that comes on in my F35 when I turn on the cruise control.

Bill Edwards 1999 Panther
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