BlueHeeler

I did a forum search with no luck. I have a 1989 c4. When I started the car today the brake boost pump did not turn on. Braking was impaired obviously. The pedal will move a couple inches and then get hard. The car does stop, but it is dangerous.

I did not get any warning lights. A few months ago I flushed the brake lines, but it has been fine since. The brake reservoir is full.

What should I look at first to find the problem? What would keep the pump from turning on?

dfinnegan

Lack of power. Have you looked at the fuses and relays?

Lack of signal. There's a pressure switch on the pump (green). If it fails to indicate the correct pressure then the unit will not operate correctly.

Are there any leaks in the front boot? Look under the spare tire. If the pressure switch fails it can leak.

You have no warning lights at all? Seems strange.

Have you access to a Bosche Hammer to check for diagnostic codes?

BlueHeeler

I do not have a hammer. There are no leaks that I have seen. I will get looking at fuses.

Thanks.

Indycam

Unplug and plug in the connectors to the pump a few times .
The power connector and the switch connector .
Then see if it starts up .

"You have no warning lights at all? Seems strange."
If the pressure switch has failed in the "I'm seeing full pressure" state , the computer would think everything is pumped up and ready to go . The computer would never tell the pump to run if its being told bad info .

BlueHeeler

You are both right. I do have a small leak and the connector sensor is off. The leak appears to be from A in the photo. The sensor B will not hook back into place. I am not sure what needs to be replaced or what the next step is.

Please tell me I do not need to replace the $2000 booster pump.

Indycam

You need a new pressure switch .
The old one ist kaput !

dfinnegan

Pressure Switch Replacement

BlueHeeler

Mucho thanks Indycam and dfinnegan.

After some review, I believe you are correct. I have no idea how it broke, started, leaking and the sensor broke off while being parked, but hey it is only $300 new to get her back to ship shape, bargain I say.

dfinnegan

Anyone work on your car lately?

I've just cut open my old pressure switch (new thread to follow) and it was difficult to remove that electrical component even after cutting a third of the housing away. That switch took one heck of a shot to snap open like that!

Indycam

The pressure of the fluid might have blasted off the broken bit .
The fluid that is dripping ...

BlueHeeler

I changed the fuel filter and a rear fuel line on my car last week. I changed the brake pads/rotors and flushed the lines (not the bomb, master cylinder, or pump), but that was in April and it has worked well since.

It does look like the switch took a hit on top, but I am confused how that could happen as it has been parked for the last week. It was working perfectly when I parked it.

Is the switch replacement a serious job? What do I need to bleed? I am a considering taking the car to a pcar shop with a hammer for a look.

dfinnegan

You will need a hammer to do the bleed as you'll have to bleed the locks. The job is not bad, but the pressure switch can be difficult to remove. Too bad we're so far apart. I'd be happy to do the job with you. I'm in Warwick, so 4-5 hrs from you.

Indycam

Doesn't just a bomb bleed take care of any air that might get in via a switch replacement ?

dfinnegan

Yeah, I suppose you are correct.

Having broken the line I felt that a full system bleed was in order.

dfinnegan

So, to be clear, I had to pull the pump from the car in order to remove the switch. The pump was placed into a wooden vice in order to get enough leverage to remove the switch. Thus the open lines.