1994 Taurus SHO 521 Error in Computer

[cmeseadoin]

Greetings all,

I have a 1994 SHO with the 3.2 ATX. The CEL is on and it is coming on erradically. ON then off then ON and off and such varying in time that it is on. I scanned the computer, only code in there is a 521 Power Steering Pressure Switch not changing state in the KOER test. I have never seen this code before in my PCM and I have just finished TONS of work to the EGR that was causing the CEL to be on all the time. This code was NOT there before. I got the EGR work done a while back and have not seen that light for a couple months. Suddenly today, now this.

So, supposedly my switch is not changing state. I scan the car, look at real time data and my switch goes from NO HIGH to YES HIGH as I turn the wheel and load the rack and pinion. It seems to work just fine. I looked for the switch on the car. Only thing I could find is the driver's side switch on the rack assessible through the driver's wheel well. I pulled the connector off and then read the data in the pcm, YES HIGH all the time so I know that is the switch. Put the connector back and it was back to normal operation. Are there any other switches because it seems to be working from the tests I have done??

Would this 521 code cause the CEL to come on like it is erradically? I guess because it provides data to the PCM, it would? I don't understand why it is faulting in the computer if I can physically turn the wheel and watch the real time data change states just fine? I am assuming that this fault is causing the erradic CEL behavior because NO other codes are there. Any insight please? Thanks!

 

['94SHO]

Check the ground strap from the rear of the intake/firewall. Did you know behind every ground screw that is on the body has paint behind it? I pulled every ground off mine, and got down to the bare metal. This sounds like a VAPS issue.
After you do the grounds, check the electric connector at the rack. If you do a
search of "VAPS", this may answer your question. Or not.

 

[cmeseadoin]

Hey there,

Thanks for the help!! I have not checked the ground strap at the firewall, will check that tommorrow in the day light. I was not honestly aware that this car was equipped with a VAPS systems, but just doing a search on GOOGLE, it appears that it does. Thinking about it, I can def. recall how the wheel has various levels of resistance say if I am turning the wheel lock to lock and not moving on asphalt vs. turning corners while driving and such, but that is sorta the way with all cars because not moving, you do not have that inertia and tire motion to assist. I am not that familiar with VAPS on this car, but I have removed and reconnected the pressure switch on the rack at the driver's firewall and drove it to dinner tonight, and she did not come on. I only went about 2.5 miles round trip though. I did play with it tonight and put it up on my lift and let it do about 5 miles and nothing either. I have not done anything to it or replaced anything though, so what might have changed I have no idea...unless removing and reconnecting that connector did something. I will have to get smart on how VAPS works. Any good sites for the SHO you might recommend? So, you think it is a VAPS issue, but with what, a ground? Thank you again for the help!

Chris

 

[93MTXSHO_STUD]

there is a real easy way to test the pressure switch.... get a multimeter that beeps for continuity. Unplug the pressure sensor (its below the master cylinder) Start the car and put the multimeter leads to the switch. It should be beeping (short circuit give or take 10 ohms), turn the wheel all the way to one side and the circuit should become an open. The multimeter will stop beeping. Also if the switch is bad your boost for the power steering will not activate at hard turns from a stop (such as parking) It will cause your car to want to die because the idle can't adjust (this isnt the case sometimes, but its common for this to happen). VAPS is a PITA i need to get mine replaced with a non VAPS. Theres test procedure too in the helm manual. The VAPS is a fairly large grey box that kind below and to the right of your steering column. Good luck figuring out your problem.

 

[Racer X]

Did you remember to turn the steering wheel from lock to lock during the KOER test? Sometimes, 90º isn't enough to trigger the P/S pressure switch.

 

[projectSHO89]

A 521 will only be triggered during KOER PCM Quick-Test. Usually, it's just a simple matter of your timing. You've already verified it works with your scan tool.

I'd look elsewhere for the cause of the intermittent CEL.

As far as site recommendations for supporting the SHO, this is it for forums-based questions. www.shotimes.com still serves as an FAQ, but it hasn't been updated in years.

Steve

 

[cmeseadoin]

A 521 will only be triggered during KOER PCM Quick-Test. Usually, it's just a simple matter of your timing. You've already verified it works with your scan tool.

I'd look elsewhere for the cause of the intermittent CEL.

As far as site recommendations for supporting the SHO, this is it for forums-based questions. www.shotimes.com still serves as an FAQ, but it hasn't been updated in years.

Steve

I concur with this statement, the ONLY thing that contradicts it is that I have done EXTENSIVE KOER tests on this car as I had many issues with the EGR system some weeks back and I must have scanned the car 20 times. I NEVER set this code in the KOER test before and so there cannot be an issue with my timing. I did the test yesterday at least 5 scans worth just to test that theory and I failed it every time. The CEL is on and off like a yoyo and there is NOTHING in the computer other than the 521 code which has never been seen before yesterday in the KOER test.

One question I have is exactly what codes will trigger the CEL during normal driving of the car from the perspective of the KOER test? When I do that KOER test, and the only code that comes up is that 521.....has that 521 been hard set in the PCM as a DTC or is that just a "surface" failure or "observation" that this test found during that timeframe and it may not be triggering the CEL? In order to get the codes on this Ford car, I have to do the KOER test to get the data whereas on my GM cars, I scan the PCM(nothing called a KOER) and I get the hard DTCs in the computer. I am just trying to make sense of the KOER test with the Ford as it relates to the actual DTCs that would be living IN the PCM and causing the CEL to be illuminated vs. a simple KOER quick test failure that probably does not trigger the CEL to come on?? Or is it that if there are ANY codes experienced during the KOER test, those codes are probably causation for the CEL to be on? I am just dumbfounded as to why the light is coming on so erradically and there is NOTHING other than a reoccurence of this 521 code at KOER test.

One note to mention, drove the car to dinner last night....about 3 miles roundtrip....no light. Drove the car to work, about 7 miles this morning, NO light. I have done NOTHING to the car other than stick it on my lift, disconnect and reconnect the PSPS switch on the Rack and Pinion and reconnect it and then run it for 5 miles in the air with NO CEL again. Is this just yet another TYPICAL glitch with this SHO?

 

[projectSHO89]

Just to reiterate, you only have 1-2 seconds to turn the steering wheel after the engine ID flashes (3X) in order to hit the testing window during the KOER test. This switch is only tested during the KOER test, it is not tested during normal driving operation. A half-turn each way of the wheel is plenty.

You can run the KOEO test to pull any stored codes. Those are the ones that the PCM saved while you were driving (if any).

About this time, if the intermittent CEL continues with no other drivability symptoms, it would be nice to get a recorder installed on the car.

Steve

 

[cmeseadoin]

Steve,

Thanks for the followup. I definitely understand the timeframe for the KOER test, but my thing with that continues to be that I have done the test over and over acting immediately to the request to turn the wheel to full right and back to center. I still fail each time and this was never an issue before, however, from what you just told me.....I am now thinking that this has nothing to do with the CEL coming on because if that switch is not tested during operation and only during KOER test, then that is not going to trip that CEL during driving. I had no other codes as of anywhere yesterday, but I am going to scan it again for fun today and see if anything has changed even though the light has been off this morning coming to work. I will post followup this afternoon to that test. Perhaps this erradic operation of the CEL means what another person suggested earlier. A ground issue! I need to check that out today. I have some tinkering to do when I get off work today!!

 

[cmeseadoin]

Steve,

Thanks for the followup. I definitely understand the timeframe for the KOER test, but my thing with that continues to be that I have done the test over and over acting immediately to the request to turn the wheel to full right and back to center. I still fail each time and this was never an issue before, however, from what you just told me.....I am now thinking that this has nothing to do with the CEL coming on because if that switch is not tested during operation and only during KOER test, then that is not going to trip that CEL during driving. I had no other codes as of anywhere yesterday, but I am going to scan it again for fun today and see if anything has changed even though the light has been off this morning coming to work. I will post followup this afternoon to that test. Perhaps this erradic operation of the CEL means what another person suggested earlier. A ground issue! I need to check that out today. I have some tinkering to do when I get off work today!!

Ok, I went out for lunch and decided to scan the car. I brought the scanner with me and hooked it up....I scanned the KOER test and this time, no 521 error. Also, I did a KOEO test and it came back with a 111 SYSTEM PASS. I then viewed the MEMORY CODES and had 5 in there: ( before you say "AH HA," let me explain where these probably came from).

Yesterday, in my attempt to locate the power steering pressure switch I found a devise on the passenger side of the engine and right directly above the power steering pump that I thought might be some type of pressure switch (before I knew it was on the driver's side of the rack and pinion). I disconnected this, what I thought was the switch, so I could make sure that my power steering pressure switch was not working by viewing the data on the scan tool with the engine on and this way I would know THAT was the switch. Well, i tried to start the car and it started but I had no tachometer, then engine did not run correctly and then I shut it off and tried to re-crank. When I hit the starter, she would not spin over freely and it was like I had a horrible hydrolock in the cylinders. It would not turn over so I quickly realized that ain't no PSPS. I reconnected it and then it was running fine, and I began looking for the PSPS in other places. I think these five codes probably came from me screwing with it.

176: HEGO sensor circuit indicates lean. (Front Side).
177: HEGO sensor circuit indicates rich. (Front Side).
212: Loss of tachometer/IDM input.
214: CID circuit failure.
543: Fuel pump circuit open, battery to EEC processor.

Seeing as I don't know if all of these or just some were triggered from me disconnecting the wrong thing and running the car, I have made a note of them all and then cleared them. If/when that CEL comes on again, I am going to immediately scan the PCM and see what codes are present in the KOEO test and what memory codes are there. Something was going on yesterday to cause the CEL to operate so erradically and I am going to go for a few drives with my scanner in capture mode.

 

[projectSHO89]

Sounds like you pulled the connector for the CID sensor or one of the harness connectors leading to it.

I'd recommend cold-booting the PCM before doing anything else to clear out the old conditions. Pull the 30A PCM/FP fuse for 10-15 minutes, then force an idle relearn before driving off.

with my scanner in capture mode

Perfect. Hope it can catch whatever is glitching.

Steve

 

[cmeseadoin]

Sounds like you pulled the connector for the CID sensor or one of the harness connectors leading to it.

I'd recommend cold-booting the PCM before doing anything else to clear out the old conditions. Pull the 30A PCM/FP fuse for 10-15 minutes, then force an idle relearn before driving off.
Steve

Yeah, I think that is exactly what I did because like I said, when I tried to crank it over, it would not even spin freely by the starter. My firing and timing was as if it were TOTALLY off. It was also not getting that cylinger identification so that has to be what I did. It was a circular sensor sorta right on what looked be the top of the power steering pump, but it appears to be right near the back camshaft.

I drove home, no codes no light. I will pull the fuse and do a relearn too. More to follow upon more drives and hopefully no issues.

 

[cmeseadoin]

Drove to work this morning, still no codes, no CEL. Very interesting.