Tranny Failed then Power Steering Switch?

[Cartman]

Sounds like there should be no continuity between the pins when there is pressure, when no pressure there should be continuity. at least that is what im getting from the passage. if there is any question please get a second opinion from your technician.

[DJmart]

Makes perfect electrical sense to me!

[quicksilverdon]

Originally Posted by DJmart

So I am guessing, no 12v reading... bad switch.?

Well, Cartman posted "When pump pressure is low, the switch is closed." closed switch = zero volts. If you weren't turning the wheel at that time, that's normal,
But, if you say you turned wheel and RPMs dropped, then a bad switch is likely.

[Cartman]

I believe the switch works by completing the circuit. one wire tot he switch will be a constant hot provided byt he ECU, the other wire will be a ground. when there is no pressure, the circuit is closed or completed. when there is pressure, the switch is open, meaning the circuit is open and no flow of voltage through it.

[quicksilverdon]

Originally Posted by Cartman

I believe the switch works by completing the circuit. one wire tot he switch will be a constant hot provided byt he ECU, the other wire will be a ground. when there is no pressure, the circuit is closed or completed. when there is pressure, the switch is open, meaning the circuit is open and no flow of voltage through it.

When a switch is open, you'll see 12V across terminals, when it's closed, you'll see zeror. Think of a fuse - if you see 12V across a fuse, it's blown (open)

[Cartman]

youll see 12 volts across the terminals reguardless of the switch position due tot he fact that your tester will be completing the circuit, not the switch. the only true way to test the switch is a continuity test. if you must test for voltage, then you place the neg(-) side of your DVOM on your neg(-) batt terminal, and the pos(+) side of your DVOM to the ground terminal of the switch. when the switch is engaged, you will have a 12v signal coming from it.
As a side note, NEVER use a test light when diagnosing new vehicles. damage tot he computer will result! ECUs dont use full 12V as signals, and most signals are extremely low amperages. using test lights may inadvertantly send full batt voltage tot he ECU and fry it. Not to mention if you accidentally get into an airbag harness.....BANG!

[DJmart]

Originally Posted by Cartman

youll see 12 volts across the terminals reguardless of the switch position due tot he fact that your tester will be completing the circuit, not the switch. the only true way to test the switch is a continuity test. if you must test for voltage, then you place the neg(-) side of your DVOM on your neg(-) batt terminal, and the pos(+) side of your DVOM to the ground terminal of the switch. when the switch is engaged, you will have a 12v signal coming from it.
As a side note, NEVER use a test light when diagnosing new vehicles. damage tot he computer will result! ECUs dont use full 12V as signals, and most signals are extremely low amperages. using test lights may inadvertantly send full batt voltage tot he ECU and fry it. Not to mention if you accidentally get into an airbag harness.....BANG!

Well i was unable to test the switch, the wires were soooo close together, and I did not have a ton of time to test. I needed a "thinner" probe to be able to get into the small connector.

For response to above, I never use a test light, nor do I have one. But I did try to use the continuity feature on the multimeter.

As for the check engine light, It has not come back on yet!! I will keep all posted. Maybe the power steering fluid has finally circulated through the lines.

I was reading in a shop manual for trouble codes, and it says you must go over 50MPH for 30 seconds before the light would show, if indeed the switch is no good... I did that yesterday, and no problem! and it was much longer than 30 seconds, highway!

Well, Ill keep you all posted

-DJ

[Cartman]

Originally Posted by DJmart

Well i was unable to test the switch, the wires were soooo close together, and I did not have a ton of time to test. I needed a "thinner" probe to be able to get into the small connector.

yeah, its a pain sometimes. if you do a lot of diagnostics you might thinking about investing in thinner probes, you can pick them up online or on tooltrucks. comes in wicked handy for backprobing small connectors.

[DJmart]

I should just buy my self a nice one....

The one i have does not have detachable probes.... *sigh*

Still no light!

[Cartman]

i guess no news is good news eh?