Ok, so i have has a power steering that likes to cut in and out are random since i got the car. Strange thing is that when it is cold outside the power steering works 90% of the time, when it is hot it only works 40% of the time.

After doing research before i found that it was most likely the ECU, so i pulled it apart to look at it. I found this:




All the contacts look good to my eye, i have also tried 2 ECU's.

So anyone have any ideas as to what this could be caused by? I am 99% sure it is eletrical. The pump and rack work perfect when it kicks in, and will work at any point in the turning radius.

Any ideas?

 

If you are certain that the problem is electrical, you should test connections via an ohmmeter. I however am not sure of the source of the problem.

 

Without looking at the FSM, I think the only tie b/t the ECU and the power steering, is a switch makes when the pwr steering is turned, and when the ECU sees that, it ups the rpms by opening a solenoid on the back of the throttle body. Called the Air Supply Valve, I THINK.

So, I don't see the ECU being the problem. Like I said, I didn't go look at the book/diagrams. Just one of those WAGS.

EDIT: Air Supply Valve would be wrong since you don't have a turbo. Probably the ECU ups the duty cycle of the BAC. Remember, just a WAG.

The belt mentioned above sounds promising.

 

check you belt tension when its cold the belt is going to be tighter hence why it works more often then.

 

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EDIT: OPPS. I see, That is the power steering contol unit, not the ECU.

 

Yeah i figure the same thing BUT i have no idea what to ohm/test. What i would really like is to know what wires to hit with 12v+ to make it come on all the time so i can test to make 100% sure that all the mechanical parts are working.

Yep, thought of this. It has been checked and it a brand nw belt and tight.

Correct, it is the box from under the steering wheel. i was told that is the one that causes problems. Am i wrong? is there another computer for the PS? where be that? my hyanes manual only shows this box.

And as i said, i am 99% sure the pump and rack are fine. when it kicks in it works perfect, and has worked at all points along the steering. seems like the pump/rack would either work or not. If i do it while idling i can hear the pump kick on as well. so the pump is just not being turned on from what i can tell.

Problem is i am lost as to how to fix this and make it work like it should. or to "hotwire" it to test it.

 

Naw, that's the only box that counts. I really should not have made any remarks. I have no pwr steering therefore no experience.

The BODY ELECTRICAL seciton of the FSM has some checks that can be made. Sorry to have muddied the water there.

 

LOL, no problem. I want too much info vs too little anyday.

 

I can see cold solder joints on the pins for where the plug pins meet the circuit board in the first picture.

 

I was hoping you would chime in.

Not quite sure what you are saying though. Those connections look good to me, no cracks or breaks in the solder that i can see.

Or is that old solder the problem?

Just to make sure we are talking about the same thing, these are the pins you are talking about right:



So i should have those re-soldered? that should fix the power steering? even if they *look* fine?

 

Icemark! is it the bottom right ones? I haven't soldered in years and I never learned proper stuff but those don't look good if I can recall what my dad taught me.

Texas_Ace, I'm probably wrong just taking a wild guess lol.

 

Note: the picture makes the contacts look worse then they are. The solder is actually perfect, no breaks, cracks or anything. what you see is the shadows from the pins.

 

What IS cold solder BTW? My knowledge about solder is limted to the fact that i can't seem to do it no matter how hard i try. I usually start a fire or melt something lol.

 

Google search for "cold solder joint" brought up this:
www.aaroncake.net/electronics/solder.htm
He covers the topic pretty well.
Those solder joints on the plug pins do look suspect (the ones you have the red line around, but note that there is also an electrolytic cap soldered in the marked area). Could be the photo, as you said.

 

Thanks for the link, though it says that cold joint have a dull gray color. ALL the contacts look the same to my eye.

And i guess even if the contacks look good they can still be bad?

What all needs to be redone?

 

Ok, now i am even more confused as to what is causing my problem.

Today i took the PS ECU to a guy that works of TV and solders all the time. He took one look at it and said that all the joints are perfect. I asked to look at it closer so he looked at it under his magnifying glass.

Came back and said it really is fine.

So the joints do not look to be the problem.

Which leaves me wondering why the PS works sometimes and not others??

Today it was a little cooler and it worked a little more. When it is real cool it works even more.

ANYBODY know what could be causing this? Having it kick in and out is getting real annoying and even dangerous.

I really want to know how to turn the PS on manually. That way I can know 100% if the pump and rack are ok. Anybody know how to do that?

 

Ok, i have been reading what little i can find on the power steering in the FSM.

On page 70 here: http://www.teamfc3s.org/main/factory...NG_DIAGRAM.pdf

You will see a check connector for the PS. What is that and hoow does that work? Will that turn the PS on all the time so i can test it? or is it supposed to have X voltage? How do you use it and where exactly is that located?

Can anyone read the wiring diagrams? I really want to hotwire the PS on temporaily to test it but can't figure out how to do it. I know that the pump sees 12V on one of the 4 wires but i have no idea which one or how to do it.

 

It looks like the test conector is a single white wire w/ a female plug under the dash. Since it's only one wire, it's gotta see 12V when the PS pump is switched on. Hook up a DMM to it and a ground point, and turn the wheel with the engine running. That should let you see if power is being sent when the PS is working or not working.

 

so the connector will have 12v when the pump should be on? or i need to give it 12v? or do i need to ground it?

Is it to tell me if the ECU is working, aka a way to see when it turns on and off? or is it a way to override the ecu and tuen the pump on? Hopfully the latter.

 

I can't say for sure what it does, but given that it's only a single wire, it must be a wire that has 12V power (+) during PS operation. If not, then it'd be a useless test connector. Again, this is only a guess since the wiring diagram doesn't specify what part of the power steering computer the white wire connects to.

Take a multi meter and plug the positive lead into the test connector. Touch the negative lead to a body gound (ie something metal). If there's current, the DMM will read ~12v. You're not going to be rigging anything to work differently. This will just let you monitor voltage. That's it.

 

The check connector seems to be a OUTPUT of the control unit and it Seems if you put a scope on that wire, you would look for patterns as shown in the attached jpg.

The ELECTRICAL CHASSIS section is where this page came from in the 88 FSM.

 

I wouldn't be so sure.
I'm no expert but the solder joints on my clock looked perfect to the naked eye (and even under light magnification), yet the clock was intermittent until I redid them.
Since you already have it apart and have nothing to lose, why not redo those joints and see what happens?

 

I think I'd just ring out the wiring to the diagams above and if it's good, change out the motor. You've already changed out the control unit. Check out that angle sensor also while your there.

Have you had your steering wheel off about the same time this problem started?

 

I hate it when your computer crashes for no reason out of the blue.... If i don't reply again then that is what happened again...

In the case of what hailers said, i have some LED wired up that might work perfect for testing PS.

Thanks, those help a lot and might even give me the awnser. I have some LEDs i used for pulling codes that i think i could make blink. Would be easier to count the codes as well.

Well you could be right, but this guy works on stuff like this all day long, he looked at it pretty close and said there was not even a hint of cold solder. Though if nothing else works i might have him do it anyways.

Yeah, i will try that tomorrow, might get a code that awnsers everything.

And no i have never pulled the steering wheel since i got the car. it came this way (it was sitting for 3 years before i got it).

What really has me stumped is why the PS works most of the time when it is cold out. Like this morning it was cooler and it worked 90% of the time. but this afternoon it went back to the normal 50% of the time.