Intermittent Low ABS/Brake Pressure

[Posti]

My Reatta's brake light and the low ABS pressure warning came on a few weeks ago, and though it took a long time I eventually got a hard pedal.  One relay had fallen down on the exhaust crossover, though it showed no external signs of heat damage.  I replaced it, and when I started the car the brake pump came on immediately and came to full pressure.  Problem is, I realized later that the relay I replaced was for the fuel pump.  What is the most likely cause of an intermittent low pressure condition?  Is the ABS pressure switch a likely culprit?  Electric motors usually work or don't, so the pump itself seems OK.  Given the long duration of brake assist, I am pretty sure the accumulator is in excellent shape.  There are no leaks, and the car currently shows no warnings and has good brakes.

[Ronnie]

If it were me I would replace the brake pump relay with a new one if you don't know how old the current one is. Then I would unplug the pressure switch and look in side the connectors for any sign of brake fluid. That is an indication is bad or going bad. Otherwise you will have to wait until the pump gives trouble again and start troubleshooting it. You can't fix it when it's working.

[Posti]

Hiya!

 

All three relays are new GM OEM replacements - I did keep the old ones, as everything was working before.  I just replaced the relays as a maintenance item.  I have not driven the car in a while due to other things going on - hope to get it out tomorrow.