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Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3362
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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I need wiring diagrams IH 3800 series bus. I'm working

Customer Question

I need wiring diagrams for a IH 3800 series bus. I'm working on the braking system. brakes are good ,pedal feels good, buzzer and warning light on in dash, no ground at pressure switch
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Daniel Wilson replied 1 year ago.

Hi my name is***** will be glad to try to help. Is this the hydraulic brake system or air? If air here is a troubleshooting guide to start with. Let me know

Customer: replied 1 year ago.
Hi Dan, it's hyd brake system
Expert:  Daniel Wilson replied 1 year ago.

Be sure to thoroughly check your harness and all grounds that they are making good contact. click here for some further info. Let me know if you need more help

Bus brake warning on

Customer: replied 1 year ago.
I don't have any grd going to the booster switch
Expert:  Daniel Wilson replied 1 year ago.

what year is this? there are some schematics on this site.

Customer: replied 1 year ago.
It's 1999
Expert:  Daniel Wilson replied 1 year ago.

Thanks for the update Patrick. I will have to see if I have any schematics for that year bus..... Let me opt out in case another expert can find something sooner.

Expert:  Daniel Wilson replied 1 year ago.

I have the ones in the link I gave already

Expert:  Jeremy replied 1 year ago.

My name is ***** ***** I will assist you.

CLICK HERE for the diagram. As you can see in the diagram, it grounds to the ECM (44) and goes through a resistor (47-b) and to the module (49). With you having no ground at all, then there could be an issue in the module since both sides of the signal are fed from it. I would check that module and the harness plug at it and see if there is an issue going on there. That module is the light for the warning lights. Chase the harness into and behind the dash. You will find a flat, black, rectangular card looking device. That is the module.

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Expert:  Jeremy replied 1 year ago.

I see you viewed this and this is still showing as a open question due to no positive (3 stars or more) rating.

Did you still need assistance with this?