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DIFFERENTIAL CONT. OFF Warning Message

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Old 01-20-2009, 07:47 PM
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Randy V
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Default DIFFERENTIAL CONT. OFF Warning Message

This warning message came on each time I started the car yesterday and this morning.

I could not get the PSD to engage, so assume 'something' happened to disable PSD.

PSD seems to be enabled again - no warning message at lunchtime and the PSD activation light illuminated as I left the parking lot with a bit of wheel spin.

Any ideas what caused the system to be temporarily disabled?
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Old 01-20-2009, 07:53 PM
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Vilhuer
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- Pump geting old and can't always produce pressure anymore.
- Pump wiring has bad contact.
- Acceration sensor or its wiring has bad contact.
- Phase of the moon is just right and Saturn is rising on eastern sky.
Old 01-20-2009, 08:12 PM
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borland
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Randy,

If you cycle the ignition switch on-off several times, the pump's pressure reservoir will lose enough pressure that when you again switch on the ignition the pump should run long enough to build the pressure back up. That's for a pump that works properly.

If you can't hear the pump run, then it might need a new one. Did you notice any leaks or check the fluid reservoir level?

If you have a diagnostic tester, you can check for faults.
Old 01-20-2009, 08:30 PM
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Randy V
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Originally Posted by borland
Randy,

If you cycle the ignition switch on-off several times, the pump's pressure reservoir will lose enough pressure that when you again switch on the ignition the pump should run long enough to build the pressure back up. That's for a pump that works properly.
That explains it!

I had the car at my buddy's shop getting a wobbly timing belt roller replaced.

He would switch the key on to push the car into/out of the work bay rather than starting it up.
Old 01-20-2009, 08:33 PM
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Rob Edwards
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It's clearly time for a Porkensioner party at Randy's house.....
Old 01-20-2009, 09:08 PM
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RyanPerrella
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Originally Posted by Randy V
That explains it!

I had the car at my buddy's shop getting a wobbly timing belt roller replaced.

He would switch the key on to push the car into/out of the work bay rather than starting it up.
wait?

Like put the car in gear D or R and then crank the car to move it in and out of a bay instead of just simply pushing the car in neutral?

If thats the case then i have to ask? "IS IT SAFE" I think thats a lazy way to move cars around and i think you risk the belt skipping or breaking with that kinda stuff. I could be wrong, but that doesnt sound like a great idea.

Of course i could be misinterpreting your words too and maybe he had the key in the ignition to put the car from park to neutral and then of course pushed it

If the PSD light continues (sounds like it only happened a couple times) then you should run the codes.

If you run codes and have NO error message and the PSD is still inactive then the fault lies with the power system (the pumping mechanism itself)

But the intermittent nature of this case sounds exactly as Borland had suggested, in which case its no longer an issue
Old 01-20-2009, 09:15 PM
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OrionKhan
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Originally Posted by RyanPerrella
wait?

Like put the car in gear D or R and then crank the car to move it in and out of a bay instead of just simply pushing the car in neutral?

If thats the case then i have to ask? "IS IT SAFE" I think thats a lazy way to move cars around and i think you risk the belt skipping or breaking with that kinda stuff. I could be wrong, but that doesnt sound like a great idea.

Of course i could be misinterpreting your words too and maybe he had the key in the ignition to put the car from park to neutral and then of course pushed it

To me, it sounds like Randy was saying that the car would be put in nuetral with the key turned on so the steering wheel would be unlocked, then pushed in and out.
Old 01-20-2009, 09:18 PM
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SeanR
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Still needs to make sure the fluid in there is primo and the pump is working as it should. Got a '94 here that must have had the original stuff in it and guess what, replacing the high pressure pump. They aint cheap.
Old 01-20-2009, 09:49 PM
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RyanPerrella
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Originally Posted by OrionKhan
To me, it sounds like Randy was saying that the car would be put in nuetral with the key turned on so the steering wheel would be unlocked, then pushed in and out.
agreed, sounds more like it
Old 01-21-2009, 01:25 AM
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GregBBRD
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The pumps are, indeed, dying from lack of service. The fluid, in the system, is brake fluid and it should be replaced every two years, just like the other brake fluid. Most cars have the original fluid in them.... We've had great success making the pumps work again..even when they are filled with water....which is common. There is a filter, with a bypass valve, in the reservior. If the filter gets restricted, the bypass valve opens and the pump takes a giant "gulp" of really nasty crap from the very bottom of the reservior. I know that no one pays much attention to the reserviors (no one stocks them and we have to get them from Germany), but they should be serviced or replaced.
Old 01-21-2009, 02:22 AM
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RyanPerrella
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Originally Posted by GregBBRD
The pumps are, indeed, dying from lack of service. The fluid, in the system, is brake fluid and it should be replaced every two years, just like the other brake fluid. Most cars have the original fluid in them.... We've had great success making the pumps work again..even when they are filled with water....which is common. There is a filter, with a bypass valve, in the reservior. If the filter gets restricted, the bypass valve opens and the pump takes a giant "gulp" of really nasty crap from the very bottom of the reservior. I know that no one pays much attention to the reserviors (no one stocks them and we have to get them from Germany), but they should be serviced or replaced.
nice, i didnt recall seeing the reservoir in the PET, but thats good to know its available individually.
The couple that ive seen have been stained from nasty old brake fluid, and im sure the filters have been gummed up too.

Obviously the built in filter replacement is nice too. Sounds like a no brainer if your going to service the PSD at all, just replace the thing.
Old 01-21-2009, 07:57 AM
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Check your fuses!! I once had the same problem and it turned out to just be a corroded fuse.

Dan
1990 928GT
Old 01-21-2009, 11:54 AM
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Tom in Austin
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I saw DIFF CTRL OFF once on my car, after cancelling haven't seen it again ... but Sean drove it and said no PSD action. He also pulled some kind of code (Sean, if you're reading this, did you ever find out what that code meant?)

I am sure the PO never had his PSD serviced. I added new fluid but there certainly could be junk in there.
Old 01-21-2009, 01:18 PM
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jorj7
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I've had that warning for the last 4 or more years. I've had it checked out and they couldn't
find any problem with the PSD. It still works fine. The concensus was that the sensor inside
the unit was bad. I've had the fluid changed a couple of times, everything operates just like
it's suppose to. Not worth taking apart just to fix the sensor.... Of course if your PSD light never
comes on, then that's another story.
Old 01-21-2009, 01:22 PM
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Jim bailey - 928 International
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check the fuse and relay in the corner of the spare tire well (right front) plug and unplug they might have gotten corroded, you do use the hatch as a traveling bar


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