Asking for a friend and couldn't find the answer in search. In my car, when I turn the ignition just before starting the engine, I hear the pump go on for a couple of seconds. In his car, the pump doesn't turn on in the first try, it does after 2-5 turns of the ignition, you'll then hear the pump go on and it stays on for about 6-8 seconds as oppose to the 2-3 seconds in my car. The green PSD light in the cluster does light up. We checked the relay and the fuse by the spare tire and they both work on my car. The PSD has been flushed at all points.

Is the pump on its way out or is it something else? He's all the way out in Portland ME and his car is a 93 GTS. Thanks in advance!

 

The pump runs until the PSD vessel is pressurized - so , this sounds correct. If there are no warnings the system is working as designed.

 

For the pump to run it means the accumulator has lost (or thinks it's lost) pressure. Does it constantly cycle on/off or does it just do a short 6-8 second burst when he turns the ignition on? I'm wondering if it's constantly cycling but he just doesn't hear it because the car's running. The way to tell is turn ignition on but not start the car for a couple minutes and listen for the pump cycling. Also, is he getting any warnings on the digital screen?

I'm assuming no evidence of brake fluid leak under the PSD or PSD slave (top passenger side of the rear-differential). Maybe put some clean cardboard under those areas and look for drips.

The green PSD icon light only turns on when a wheel breaks traction and the PSD's engaged. It's not an ops-check light per se.

 

What I was describing was with the engine off. It does turn on for a short 6-8 seconds with engine off but not on the first try. The pump goes on anywhere from the 2nd to 5th turn of the ignition with engine off. There are no error messages displayed.

Logically, it does sound like what Kevin in Atlanta said, it hasn't lost pressure so the pump doesn't turn on. It's just that on my car, it always goes on for 2-3 secs on the first try and it also did that on his car before he flushed the PSD, although it did take him 2 years to get to it and the car wasn't driven for a year and a half.

 

Yep, if you haven't left out any details and the "differential controller off" is not displayed within a minute of start up you are good.

 

+1

when was the last time the system was flushed? that seems to solve a (surprisingly) good number of issues.

 

I'm with Kevin. FWIW- I'd tell your friend to go find a big wet parking lot early on a Sunday morning and do some figure-eights trying to break traction. When the PSD locks up, he'll know--and he'll know everything is 5/5. I try to do it a couple times a year as a PMI and make sure all the moving parts are moving.

 

I worked on a GTS last week and it was a low miles car what was happening was when the key was turned on the PSD. Pump would continue to run and not shut off
The owner pulled the relay and fuse and had me service the system with a fluid change
I got the old fluid out and with fresh fluid the pump would not turn off indicating that it was not getting fluid
i put my myti vac pump on the tank pumped the tank to 10 psi and powered the pump and it started pumping up the system as the level began to drop and then the pump shut off
i bled a few tanks through the system and all is well

 

How can I tell if my PSD is working correctly?

No diff control off error but the green PSD light doesn't illuminate at initial power on.

Years ago the green PSD light would flash on when experiencing wheel spin like when cornering and I could feel the brakes being automatically applied to the wheel.

Not any more.

 

If you were to hop in your car and turn the key to the first position and NOT start it, you should see the check engine, stop lamp and PSD lights light up on the right-hand side of gauge cluster. Does it light? That won't tell you if the system is working, but at least you'll know if the bulb is working.

 

No it doesn't light. Could be a burned bulb.
Will investigate when I pull the cluster to fix the voltage gauge and install instrument LEDs.