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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8726
Experience:  I am ASE Master Truck Certified.
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2000 sterling with 3406 in it no jake brake

Customer Question

2000 sterling with 3406 in it no jake brake
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 1 year ago.
Hi. Thanks for asking your question! I will try and help you out.
Can you get me the engine serial number please?
Are you saying the jake brake is not working?
Customer: replied 1 year ago.

yes jake is not working

Expert:  Cat Man replied 1 year ago.
Thanks for the information.
Can you get me the engine serial number please?
Expert:  Cat Man replied 1 year ago.
Hey Mark,
There are three things I have seen that will cause the Jakes not to work. They are:
• Engine retarder switches. If there is a problem with the switch or the wiring going to it, the Jakes will not work. To verify they are working, you will need to have someone connect a service tool and monitor the status of the switches.
• Accelerator pedal position sensor. The accelerator pedal must be going back to idle or 3%. This is the only way the ECM knows you are not pushing the accelerator. To verify this, you will need to monitor the status with a service tool.
• Clutch switch. The status of the clutch switch should indicate that the clutch pedal is being depressed and released. When the clutch pedal is depressed the status should indicate ON. When the clutch pedal is released the status should indicate OFF. To verify this, you will need to monitor the status with a service tool. I have seen the clutch spring wear and not return the clutch pedal all the way back up. I would try pulling the clutch pedal back up and see if the Jakes work. You may have a weak spring.
Please reply back if you need more help or have more questions. I am happy to assist.
Customer: replied 1 year ago.

serial # ***** *****

Expert:  Cat Man replied 1 year ago.
Thanks for the information.
Just follow the info I posted earlier. I'm sure it's one of those items. Most often I find the clutch switch the problem.
Customer: replied 1 year ago.

does the clutch switch get power from computer

Expert:  Cat Man replied 1 year ago.
Basically when the switch is closed. The switch applies battery ground to the ECM. When the ECM gets the ground. It knows the clutch is off.
Customer: replied 1 year ago.

so the switch for on and off and clutch just are a ground to ecm

Expert:  Cat Man replied 1 year ago.
that is correct.
Customer: replied 1 year ago.

clutch switch is working and the throttle pedal is working to show on my computer . computer shows the jake is disabled

Expert:  Cat Man replied 1 year ago.
Thanks for the information.
How about the status of the jake switches?
Does the throttle pedal go to 3%?
Customer: replied 1 year ago.

yes on throttle pedal and I cant see switchs

Expert:  Cat Man replied 1 year ago.
I see.
If the throttle pedal and clutch switch are working. All that's left are the jake switches themselves. It could also be PTO switche is on, if you have PTO switches. If you do not. I would suspect the jake switch or the wiring connected to them.
Please reply back if you need more help or have more questions. I am happy to assist.
Expert:  Cat Man replied 1 year ago.
Hey. I just wanted to see how things were going. Please let me know if you need more help. I am happy to assist. If my information was helpful, please leave a good or higher rating so that I receive credit. Thanks.
Customer: replied 1 year ago.

do you no the number for the ecm for the jake switch wires I think they are 23 and 40 but not sure

Expert:  Cat Man replied 1 year ago.

Yes sir. You are correct. They are pins 23 and 40.

Please reply back if you need more help or have more questions. I am happy to assist. Also please do not forget to leave a positive rating. That's how I receive credit for answering. Thanks.

Customer: replied 1 year ago.

I have 2 switch in cab one for on and off and one for low -mid- high and they should just send ground to ecm

Expert:  Cat Man replied 1 year ago.

Yes that is correct.

When it's on low it should send ground to pin 23 to turn on Jakes for 3 and 4. When it's on medium it sends ground to 40 to turn on Jakes 1,2,5 6. When it's on high it sends grounds to 24 and 40 and turns on all of the jakes.