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Jake brakes wont work. 2003 pete 379 c15. Cat told me to…

Jake brakes wont work ...

Jake brakes wont work

Mechanic's Assistant: What's the make/model/year of your truck? Engine type?

2003 pete 379 c15

Mechanic's Assistant: Are you fixing your truck yourself? What have you tried so far?

Yes, cat told me to unplug the two wire connector to the micro switch and use a jumper wire to see if the jakes started working if they did then we would know the micro switch was bad well we did that an still no jakes

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Customer reply replied 4 years ago
whats the response time
Answered in 1 hour by:
3/8/2018
Technician: Daniel Wilson,
 replied 4 years ago
Daniel Wilson
Category: Medium and Heavy Trucks
Satisfied Customers: 15,127
Experience: Owner at DJ Wilson
Verified

Hi My name is***** with me while I pull some info. Any fault codes logged?

Check engine light on?

There is a clutch switch and brake switch. Either of them are common failures

Let me know your engine serial number prefix and I will likely have the proper diagram for your engine.

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Customer reply replied 4 years ago
the check engine light flickers on and off had a code 61 and 46 i got off toggling the resume switchmbn11088
Technician: Daniel Wilson,
 replied 4 years ago

110-00

61

High Coolant Temperature Warning

100-11

46

Extremely Low Oil Pressure

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Customer reply replied 4 years ago
ya im not sure its never been hot on methe oil pressure has never dropped on me either
Technician: Daniel Wilson,
 replied 4 years ago

As long as you know your oil pressure is good and its a false code from a wiring or sensor problem

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Customer reply replied 4 years ago
the only problem i seem to be running in to is the jakes dont want to trip at all and the cruise works but some times decides not to but today it idled up every time i used it but no jakes
Technician: Daniel Wilson,
 replied 4 years ago

Ok. Let me dig up the engine diagram.... I can help with full chassis schematics if interested as well in a premium service too

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Customer reply replied 4 years ago
ok every schematic i can get will help
Technician: Daniel Wilson,
 replied 4 years ago

Click on this link

Service info

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Customer reply replied 4 years ago
is that the same as a c15
Technician: Daniel Wilson,
 replied 4 years ago

Yes

Daniel Wilson
Category: Medium and Heavy Trucks
Satisfied Customers: 15,127
Experience: Owner at DJ Wilson
Verified
Daniel Wilson and 87 other Medium and Heavy Trucks Specialists are ready to help you
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Customer reply replied 4 years ago
were would you start. Cat told me to start with the wisker switch behind the air tank on drivers side unplug it and use a piece of wire to jump it and they said that would make jakes come on well it didn't so now im really wanting to know were do the jakes get there power from
Technician: Daniel Wilson,
 replied 4 years ago

The ECM controls the jakes but it sees clutch and brake switch status and the Low, med, high switch status

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Customer reply replied 4 years ago
it could be in the ECM I had one guy tell me that I needed to replace it
Technician: Daniel Wilson,
 replied 4 years ago

Yes it could be ECM related but a software reflash could resolve it but that is last once you have checked the switches and wiring

Click this link

Jake manual

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Customer reply replied 4 years ago
could the throttle position sensor cause it to have this problem
Technician: Daniel Wilson,
 replied 4 years ago

I added another link to the private contact window.

Probable Causes

  • Engine retarder switches
  • Accelerator pedal position sensor
  • Clutch switch

 

  • PTO on/off switch

It is easier to monitor these switches using Cat ET or a scan tool that reads live data to watch switch status,

Other wise you will need to jump them as suggested but wont tell you if the wiring is bad as viewing live and seeing no response would.

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Customer reply replied 4 years ago
yep well i think im going in the rite direction then with the schematics thank you
Technician: Daniel Wilson,
 replied 4 years ago

Pleasure to help.

If the brake switches, the clutch switch, and pedal are all working, I would suspect a leak at the engine brakes. The reason I say this is because if the pedal is going to 3%, and the clutch switch is closed, the engine brake should work.

However If there is not power going to the brakes so the last thing to suspect is an ECM problem as we discused.

If mechanical hense causing low oil pressure.... Remove the valve covers and inspect. You can run at idle and manually engage each solenoid by pressing the center on each one.

Do not touch the injectors as it is dangerously high voltage though.

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Customer reply replied 4 years ago
ok is the only way to check current through all those switched with a computer or can we use a volt meter
Technician: Daniel Wilson,
 replied 4 years ago
You can test voltage with a voltmeter and also you can run continuity checks with your ohm meter as well and test grounds it just makes it faster watching Switch status live on the computer
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Customer reply replied 4 years ago
Hi there weve done some checking i have 12 volts at the jake brake switch on a black an white wire
Technician: Daniel Wilson,
 replied 4 years ago
Thanks for the update. I'm not where I can look at the diagrams right now as I'm mobile on my phone. Did you not get the link of 41 pages of schematics for the truck that I posted last night? The diagrams should be in there to compare what you have. Let me know if you had trouble accessing those diagrams as I won't be able to look this up for you until I get back to my computer later on.
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