QuestionI have an instrument panel light that flashes and a chime that sounds that is indicating a brake reserve warning. The owner's guide tells me that I may have inadequate hydraulic booster pressure or a reserve pump system failure problem. What exactly are these? and what do I look at to eliminate this warning light? The truck is an automatic transmission. It has an electronic engaging PTO for the dump. The dump works fine and the brakes seem to be working fine as well. Another thing, this indicator does not go on every time we start the truck. We can't figure it out and we don't want to take it to the dealer unless its something we can't fix.
AnswerHello Kurt,
The hydraulic pressure it is talking about is not the same hydraulic as the dump system.
Any system that is fluid operated could be called hydraulic.
Your brakes may have a hydroboost system, which uses a power steering pump for pressure assist.
It is entirely possible that pump reservoir is low on fluid.
There may also be a pressure sensor in that system that is either not working properly, or may be working properly, and there really is lower pressure than desired.
One cause for low pressure would be a loose fan belt.
There could also be an auxiliary power brake pump, like an ABS antilock brake system pump, that operates automatically, and there could be a problem in that system, like a blown fuse, or bad relay.
I would check the fluid levels and belt first, and look around to see if there are pressure hoses going from the power steering pump to the brake system, probably between the master cylinder and the firewall. That takes place of a vacuum booster.
You really need to know exactly what types of systems you have in order to understand how they are supposed to work.
Van
