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Discussion Starter #1
Hello all --

Again, it is great to see such support for the Taurus!

Here's my story-

My wife was on her way home from the airport last Wednesday, when I get a call that she is at a light and the car has stalled and won't start. Luckily she as just a mile down the street, so I towed it home with the Willys.

The Taurus is a 1993 sedan -- 3.0 Vulcan (pushrod) V-6 with an auto trans. It has over 120,000 miles on it.

"The car just shut off" as she was sitting at the light.

So... I diagnosed that it has plenty of spark ( I have an inline bulb-type testor hooked into one of the spark plug wires) and plenty of fuel pressure, that doesn't fade or anything (installed a fuel pressure gauge on the rail).

The fuel pump/fan relay module was humming/vibrating like crazy, so I replaced it. I figured that was the end of it, but no, it still wouldn't run! Then I figured that mabe my buddy down a NAPA got me the incorrect replacement relay module. Sooo I went into the old one and removed the fuel pump relay from the printed circut board. I then installed a harness & socket that allows for a standard 12V automotive relay. Yes, I was going alittle crazy at this point.




Sooo, what I have been able to accomplish is this: I turn the igntion to run, and the pump runs, I then remove the (butchered-in) fuel pump relay (from the wires/socket that is now sticking out of the module) and then crank the starter (via the ignitoin) and the car will run until it runs out of fuel pressure. if I jam the pump relay back in while it is running, it stalls inmediately. If I hotwire the fuel pump by running it right off the battery (or a battery charger) the computer will not give me spark.

So my diagnosis is that the PCM is giving spark and fuel pressure, but will not fire the injectors. Why??? :angry:

I have and OBD1 reader. These are the codes it has given me. Upon further discussion, research, and head scaratching, it seems it might be one of the sensors/switches int he trransmission that is causing the engine to not run??? If that is the case. Will someone PLEASE explain to me WHO designed this PCM and WHY??? :angryfire:

Sorry -- the codes:

#326, #628, #634, #327, #565, #543


I have a FSM but it does not seem to have these codes or anyway of troubleshooting the PCM. As far as I can tell, this is done in a seperate manual.

Any and all help will be GREATLY appreciated. We need to get this car back on the road!


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check here


Sounds like you have a similar problem. There's a diagram in there that will show you how to jump the fuel pump to make it run all the time too, instead of using the relay method you used. Very ingenious thinking though!

And when you get a chance, pics of the Willys!
 

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These are what the codes mean that you were able to pull. I'm not sure totally what they all mean, I just figured they might be of some help to you. Maybe someone else can chime in who's a little more experienced than myself.

326 – “Pressure Feedback EGR (PFE) sensor or EGR Pressure Transducer (EPT) – signal voltage lower than expected”

327 – “EGR Valve Position (EVP) Sensor, Pressure Feedback EGR (PFE) sensor or EGR pressure transducer (EPT) – signal voltage to low”

543 – “Fuel Pump (FP) circuit open connection – Electronic Control Assembly (ECA) to battery”

565 – “Cannister Purge (CANNP) Solenoid – circuit failure.

628 – “Excessive converter clutch slippage”

634 – “Manual Lever Position (MLP) sensor – signal voltage higher or lower than expected”
 

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Discussion Starter #4
The pump will run when I ground that terminal, but it will not give me spark.

I'll do some searching through the harness-- it sounds like one of the trouble spots is near the relay module in the engine compartment. I'm also going to check the drivers floor-- as mentioned in that article.

I forgot to mention that when the relay Module (what is it called again?) will buzz when the key is turned on-- it will buzz less when the fuel pump relay is removed.

We do have a new PCM on its way-- $50 on ebay. I have a strong suspicion that it will not be the culprit.

Thanks for the props-- it was a momemnt of desperation!

Jeep pics?- there are a few here

Big thanks on the codes. Can anyone elaborate on the failure codes, please?

I am especially intersed to know anything more about #543, #628, & #634. From what I read about the convertor clutch and the MLP-- if one of thease fails, it can cause the engine to stall and possible not start. :blink:


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Nice Jeeps! Now back to the Ford:

-Code 543 will sometimes come up when the car stalls. I wouldn't worry about it until you get the car running again. If it comes back, then we'll address it.

-Codes 628 and 634 are also indicitave of having a short somewhere in the harness, at least in this case when you have a bunch of codes for low voltage. The sensors associated with these codes (MLP and TSS) have an input voltage, and an output voltage that the PCM is expecting to see. If the output voltage falls out of normal range, the PCM will kick a code for it.

-Code 326 I have DPFE circuit voltage lower than expected.

-Code 327 is DPFE output circuit below minimum voltage.

Makes sense, at least in my feeble mind ( :) ), that the sensors are not getting correct voltage due to a short somewhere, resulting in the output voltages being too low/incorrect also.

Hope this helps!
 

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Discussion Starter #6
OK-- short hunting I will go--

Again-- any other perticularly common places to look besides the places mentioned above? (near the ICRM inthe engie bay and on the drivers floor)???

Thanks for the support!
 

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I've never experienced the driver's floor problem, but somedude is a mechanic in a shop so I'd definitely take his advice on that.

On the ICRM harness, take off the hard plastic loom when you check it. Also, the gentleman in the other thread I posted a link to, carroll, found that his PCM harness was burned, you may want to check that out also.
 

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Discussion Starter #8
Well, after prying the harness off the rear side of the engine, I noticed that where the ground wires for the engine harness attach to the radiator bulkhead was looking like something on the Titanic. :huh:

That little voice said "that's your problem!!!". Well I still inspected the harness-- especially the part where it runs along the backside of the engine-- right near the exhaust manifold. The shell looked fine and the wires were in perfect shape. SO with all that put back together I turned my attention to the grounds. At first, I simply cleaned them with the wire wheel. Upon fastening them to the bulkhead I found that the OEM sheet metal screws do a horrible job of creating a nice ground. they promptly stripped out. It also occured to me that it was very strange for there to be two ground connections right next to each other. :huh: Why didn't Ford save the $0.02 and use ONE screw??? Besides, with 2 points of contact, it invites trouble.

After photo of the round-- I stuck one of the offending sheet metal screws in to help identify the perpetrators :angryfire: See all that pitting?? Imagine what the terminals looked like! I can't believe I didn't notice the mess sooner. I wish i has a before pic!



Then I took a look at the plug that allows for seperation between the ground terminals and the rest of the harness. Why the $&%# did they put that there??? If a person needs to remove the harness-- just unbolt the ground terminals that are 10" down the wire! Anyway, it was all green and corroded. One of the wires had actually broken off by itself (maybe the cause of my woes).

Pic of the offending plug




So I taught the entire cluster f**k a good lesson. I cut the plug out of the circut and soldered the wires together. I then drilled a new hole for a 5/16 bolt near the edge of where the OEM ground mounts were. I then wire wheeled the paint off the area and put down a light coating of silicone grease on everthing before installing BOTH grounds and cranking the shite out of that 5/16 bolt!




Well. I have to say I cannot believe the differnece a good ground can make! It starts right up. The transmission shifts like never before and doesn't hesitate or slip between shifts anymore. To any and all Taurus owners I strongly suggest upgrading this ground!

I've heard it before and am kicking my self in hindsight. The crazy problems I was having should have first led me to check the grounds. It is amazing what a 'floating ground' will do.

I once was working on (one of) my Jeeps' tail lights-- I was suprised to find that by not having the light grounded (because I had it hanging off the vehicle) the engine would crank when I shifted the trans into reverse! (this is with the key off!) :blink:


anyway-- if you have read this far-- thanks for listening! :)


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Great job! I should check that on my 93. With all the work I've done to it, I never redid that ground.
 

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i know this post was way back in 2007 but i am having a problem in 2012... I got my 94 taurus back after getting a new (new to me but used in general) upper intake plenum put on from a large vacuum leak. I then find out my rear drum brakes are pretty bad. But oh well. I thought "I will check some prices and get to it as soon as i can cause im not paying pep boys 600 bucks to do my rear brakes". On friday night, I used seafoam for the first time. Nothing was running bad. I just wanted to clean out the pistons and cylinders and also the fuel. I decided not to put any in the oil crank case. So I suck 1/3 into a vacuum line (I didnt use the brake booster line cause it goes into a T-junction that has so many other hoses that I got dizzy and didnt use the PCV valve cause I was told the vacuum line is too large so I used this very small line thats right to the left of the plenum). Anywho, so I used it, put the other 2/3 in the gas. Saturday I had a bunch of places to go and the car drove fine. Sunday I go out and we fix my bumper and I used a little syphon pump to get the old nasty fluid out of my power steering reservoir and replaced it with some new tranny fluid. Then my idea was to start the car and have my brother turn the wheel back and forth to bleed the power steering and to hopefully run some of the new tuff through the lines so that I could repeat the process a couple times. literally right before we did that, I had sprayed some PB blast down from the top of the engine bay to try to hit this rusted square fitting on my trans cooler line cause I was thinking about flushing my tranny next. I eventually hit my spot but i MIGHT have squirted a little in the area of some wires. I was standing at the front of the car obviously and the area I sprayed down had the upper radiator hose in my way, the battery to the right of that, and the constant control relay module to the left with the wiring harness in the area. Remember that part...


so I get him to crank it and the engine would turn over but not start. I immediately yelled cause it took me FOREVER to find out why it wouldnt start before I gave up and got it towed to Melvins auto for them to tell me it was a vacuum leak at the plenum. So I just thought bout all that crap and how I thought those days were over for a little while. I then tried turning the ignition. Same thing. Thought it was the battery. We tested it and its reading like 12.7 volts or even 13 so its good. Then I noticed at the on position before you crank it, there was a weird noise coming from the rear. it sounded like it was coming from the area where my fuel filter is. So my bro went over to listen and sure enough it sounded like it was around that area. I also noticed that with a cold engine, as long as my key was in the on position, the cooling fan would run. I dont think its supposed to do that?


To make an already long story a little shorter, I was thinking fuel pump. Then melvins tells me to get a fuel pressure guage and see if it holds pressure in the first 4 seconds. Autozone tells me it could be the fuel pump relay. But lucky me, from what I have read about on other forums on google, my car dosnt have an accesable relay. I am pretty sure its in the constant control relay module. I am not hearing that weird sound when I turn the car on anymore. so part of me is thinking the fuel pump still, part of me is thinking the fuel pump relay but that would mean replacing the entire CCRM and I dont wanna! And the other part thinks it MIGHT be a short somewhere when I sprayed the PB blast.


DOES ANYONE HAVE AN OPINION??????? I NEED HELP!!!!! IF IT IS THE RELAY, IS THERE ANYWAY TO GET TO IT? IF IT IS A SHORT, HOW DO I FIND THE SHORT AND WHAT DO I USE TO DO IT? IF IT IS THE FUEL PUMP, IS THERE A WAY TO TEST IT SOMEHOW WITHOUT DROPPING THE ENTIRE GAS TANK AND TAKING IT OUT? THE TAURUS SAT FOR ABOUT 2 MONTHS WITH A 1/2 TANK OF GAS BEFORE I PICKED IT UP THE DAY i GOT IT WHEN THE PLENUM GOT REPLACED. IT WAS NOT EVEN 3 DAYS LATER WHEN I DID THE SEAFOAM. CAN MAYBE STALE GAS MIXED WITH SOME SEAFOAM CAUSE THE PUMP TO GO BAD?
 
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