98 'Tour blowing PCM fuse #9

Contour Enthusiasts Group Archives

On my Contour -- '98 (built 9/97) V6 ATX w/ 98K mile. No mods at all, only work I've done since buying her in Feb was replace the water pump.

Driving north on I-71 on Saturday near Strongsville, OH and 110 miles from home, when the engine just STOPS. Cold. All the needles on the dash immediately drop to zero (so even though I'm coasting, the MPH reads 0). I manage to coast to the side.

Eventually find that fuse #9, blue 20A, for the PCM is blown. Call a friend, they bring a new fuse, it blows as well on the first turn of the key. Car towed to next exit (Center Towing, Strongsville, OH gets a :thumbsup: ), and then girlfriend's father trailers it the 110 miles home for me (Thank you!). Now it's on the street in front of the house, and I need to find the short.

The little that I've found searching is the fuse blowing on startup, I haven't seen an example of one blowing while driving (after nearly two hours of trouble free driving).

Other than grabbing my multimeter, and my Ford CD, are there any hints about where to start? Tracing the wiring harness is going to be a royal PITA, and any shortcuts are most appreciated.

Thanks!

This might be a tough one. You will definitely need that meter and the schematic from the CD.

F9 feeds the PCM power relay in the underhood panel. The output goes to the VSS, the EVR solenoid, the PCM, EVAP valve, the CP solenoid, the MAF, the IAC valve, the ATX (supply for all solenoids), IMRC module, and the AC WOT relay.

Locate the load side of the PCM relay, and verify that the short to ground still exists. Then, unplug each device, one at a time, and see if the short circuit goes away.

If you're lucky, one of the load devices will be the fault and, once disconnected, will remove the short circuit.

If you're not lucky, you'll have everything disconnected and the short will still remain. If so, you'll have to locate each of the relevent splices, undo each, and see which leg has the short.

The EVTM diagram is not for the faint-of heart. It is, IM(Not So)HO, the worst diagraming format that Ford ever used for it's schematics and was only used for a model or two, including the Contour and Cougar.

If you get stuck, let us know.

Steve

Thanks Steve. I poked around last night after getting the yard mowed, and it looks like there is a short to ground on one of the PCM relay connectors. It's not good when you get continuity from the same pin to both the positive battery cable AND the negative battery cable at the same time!

If anyone else has any insight, I'd appreciate it. Otherwise I guess it's time to start pulling plugs.

It sucks that it's on the street, it'd be easier if it were in the driveway.

One of the terminals is supposed to be connected to ground. That's the low side of the coil. The other side of the coil should go to the load side of F4.

The COMMON terminal should go to F9, the NO (Normally Open) terminal is your load side that connects to everything above.

Do not attempt to measure resistance in a circuit that has power. You will either damage the meter or will get bogus results.

I do not have the Contour handy (wife drove it to work) to get exact pins for you to check. Maybe tonight...

Hey, at least the car is at home, not along the highway somewhere.

Steve

Now that the rain has stopped, I need to get back to troubleshooting this...

What is the CP solenoid??

I've checked the EVR solenoid, MAF, ATX solenoids, IMRC and A/C WOT relay. Need to check PCM, EVAP, IAC, and "CP solenoid". But don't see that in the book, wish the CD had better search.

Thanks

OK, figured out that the CP solenoid is the Canister Purge.

I have disconnected all of the following load devices:
ATX solenoid plug
EVR solenoid plug
MAF plug
IMRC plug
A/C WOT relay
PCM plug under P/S reservoir
EVAP canister plug
IAC plug

The short on pin 3 of the PCM relay remains.

Only load device I didn't disconnect was the VSS plug. I jacked up the 'Tour and found the VSS by hand, but how do you disconnect it? Does the whole sensor need removed? That ain't happening on the street!

Is it my luck the short is the last load device I can't get to (VSS) or is it in the harness... somewhere...

Since it happened while the car was cruising on the highway, any suggestions what might have gone poof at that time, as a starting point?

Originally posted by Linkman:
..The short on pin 3 of the PCM relay remains.

Only load device I didn't disconnect was the VSS plug. I jacked up the 'Tour and found the VSS by hand, but how do you disconnect it? Does the whole sensor need removed? That ain't happening on the street!

Is it my luck the short is the last load device I can't get to (VSS) or is it in the harness... somewhere...

Since it happened while the car was cruising on the highway, any suggestions what might have gone poof at that time, as a starting point?

Yes, according to Haynes, Pin 3 is for the VSS. The wire should be White/Blue or White/Violet. A few months ago, a CEGer had a short too and it was determined to be a VSS wiring issue. The mechanic just ran a wire from the VSS to the PCM.

Edit. Here is the thread on the VSS wiring.
http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=trouble&Number=1165885&Forum=trouble&Words=mechanic%20vss&Match=And&Searchpage=0&Limit=25&Old=1year&Main=1165885&Search=true#Post1165885

Some instructions on removing the VSS
VSS change by unisys.

"VSS (Vehicle Speed Sensor)

I had to change my VSS late this afternoon, so I thought I would walk you guys through the process on my Duratec/CD4E. It's really not all that bad, except unplugging the connector. My symptoms were pretty simple... Bouncing/in-accurate seedo and once that was bad enough, the tranny would not shift properly.

- Secure the vehicle, in the air, safely.

- Remove your air cleaner & tubing.

- Reach down, under the brake booster, and locate the VSS connector. You can actually see it better from the bottom, just no way to actually reach it from there. It will take some serious single handed twisting to disconnect this connection, but don't give up!

- From under the car, use a 5/16" wrench to remove the single bolt from the VSS retainer. * Note that this retainer looks like it is upside down, with a tab resting on the case of the tranny. Don't fret! This is normal, but be sure to replace the retainer in the same way that it was removed.

- Grasp the sensor body and lightly wiggle it out of it's location. Use gently force when wiggling, but apply steady pressure upwards. The sensor body should slide right out. Do not jerk upwards on the sensor, when removing it, or you will run the risk of gear coming off the end of the sensor. This is not a real big deal, since the gear itself is about an inch tall. Along with the added shaft that is part of the gear, the gear assy is probably around 4 inches long. You should be able to grasp it with a pair of crooked needle nose pliers, but it would be one hella tight fit!!

- Once the sensor is out of the case and you have removed the gear assy from the sensor body, use a rag to wrap around the body of the sensor base. This part of the sensor is metal, so we don't want to damage it. Use a pair of pliers and grasp the metal part of the sensor. LIGHTLY! Do Not Squeeze Hard!! Just apply a small amount of pressure here. And use a 1" wrench on the plastic part of the body and seperate the two halfs.

- At this point, you get simply reverse. But something that I should note here... There is a seal on the metal half of the sensor base. Be sure to inspect this seal closely or better yet, just replace it. Also, be sure to clean everything really good and lube everything down with CLEAN ATF before putting it all back together.

Part number of the sensor - F-F5RZ-9E371-BC

Cost of part - 44.67 + tax = 47.80

Part was purchused from local Ford Dealer

Reason for sensor replacement - Notice about a week ago that when traveling over bumpy roads, that my speedometer would fluctuate +/- 5mph. Monday, of this week, it progressivly got worse (of course) and the speedo would actually stay at 0 when taking off from a stand still, as well as droping to 0 when I let off the gas. In only 60 miles of driving, on that day, it managed to toast the ATF I had in there, which only had about 5K on it. Yes, I have also changed my ATF as well."

From Autozone for VSS change
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1b/cb/ad/0900823d801bcbad.jsp

This may be a dumb question but did you unplug the PCM to see if it was blown. I'v seen it happen.

Originally posted by 2X95SEs:
This may be a dumb question but did you unplug the PCM to see if it was blown. I'v seen it happen.

I have disconnected all of the following load devices:
ATX solenoid plug
EVR solenoid plug
MAF plug
IMRC plug
A/C WOT relay
PCM plug under P/S reservoir <<<<<<<<<<<<<<<<<<!!!!!!!!!
EVAP canister plug
IAC plug

Quote:

- Reach down, under the brake booster, and locate the VSS connector. You can actually see it better from the bottom, just no way to actually reach it from there. It will take some serious single handed twisting to disconnect this connection, but don't give up!

Ah ha! Thanks! I didn't bother looking for directions last night once I came in, that was the last connector I had to unplug, and I couldn't figure out the plug for the life of me while laying under the car. That makes it better if I can get it unplugged from up top.

Being under the car on jackstands in the street is not my favorite thing.

I'll check the VSS first chance I get, and then if that's not it, I guess I get to study for my advanced wiring harness degree.

Thanks for the help guys, and keep any potentially useful bits of info coming my way.

Bumping to update, and ask a question...

I got back to this last night - managed to disconnect the VSS from above, and found the PCV valve not inserted into its tube at all, so at least one other problem has been fixed. And discovered I'd disconnected the TR sensor, not the ATX hardware unit, so did that correctly this time as well.

Unfortunately, neither VSS nor ATX hardware unit was the cause of the short. So... time to trace the harness

Question -- So now that I have to start unwrapping splices and such to trace the PCM power relay wire, what should I use to rewrap the bundles? I've never had good luck with regular electrical tape, the adhesive softens in the heat. Are there high-temp tapes or some other product?

And as always, any hints or tips are appreciated.

Update, and a question on splice locations.

Weather, work, and other obligations have finally allowed me to return to this...

Where is S59, and S178, on a 98 Contour ATX V6?
The Ford Service CD says "S59 engine compartment - center", and "S178 - engine". Any Ford techs know where those are? Do I need to remove the UIM, or get to them from underneath?

If so, I'm going to have to find some friends to help me push it up onto the driveway, don't want to do that in the street.

Thanks!

Did you pull the PCM connector? See if the short goes away. I will take a look at my 1995 electrical manual which is similar to the 1998. It might be worth getting the 1998 Ford Service books, and/or Alldatadiy.com online information. See if there is a 1998 Ford electrical and main manual, on eBay. The CD has a lot of information, but the books are easier to navigate. Check this topic tomorrow afternoon..

I have the 98 EVTM hard copy. It is as big a piece of crap as is the CD version in terms of usability..... Don't waste time or money on it if you already have the CD.

It must be for 1998 they messed up what I find are useful diagrams in the 1995 version.

Originally posted by Linkman:
...Where is S59, and S178, on a 98 Contour ATX V6?
The Ford Service CD says "S59 engine compartment - center", and "S178 - engine". Any Ford techs know where those are? Do I need to remove the UIM, or get to them from underneath?
..

Can't tell you where exactly it is but...

according to Haynes, from Pin 37 and 57 on PCM, both are Green/Yellow which goes to S178.

From S178, it is Green/Red which goes to S59.

From S59, it branches out Green/Blue to (1)S66 and (2)S147.

From S66, it branches out Brown/Orange, Green/Yellow and Green/White to the ATX solenoid valve unit.

From S147, it branches out Green/White to Radiator High Speed Relay (R2?) in Power Distribution Box, Green/Blue to Radiator Cooling Fan Relay (R5?) in Power Distribution Box, and Green/Yellow to Power Supply Relay (R11?) in Power Distribution Box.

Hope this helps. Good luck.

Originally posted by projectSHO89:

Originally posted by 2X95SEs:
This may be a dumb question but did you unplug the PCM to see if it was blown. I'v seen it happen.

I have disconnected all of the following load devices:
ATX solenoid plug
EVR solenoid plug
MAF plug
IMRC plug
A/C WOT relay
PCM plug under P/S reservoir <<<<<<<<<<<<<<<<<<!!!!!!!!!
EVAP canister plug
IAC plug

Pull the computer - the little box in the kick panel, unplug it - plug in the 20 amp fuse and see if it blows. If it does, the problem is from the battery to the pcm feed or one of the powered circuits. If it doesn't, the pcm is shorted internally. Lots of floating grounds under the hood of the tour to fool a meter. My wiring diagrams from Ford don't match my color coded harnesses, so make sure they are right.
I've rewired cars that had melted harnesses and found lots of incorrect diagrams.

Thanks for the responses guys.

I've managed to narrow down the search though - it's in the harness somewhere south of C3001 - the large black plastic connector mounted on the driver side strut tower - but it's north of C120 - one of the connectors on rear passenger side valve cover, near the strut tower. So it's somewhere in the harness that connects the EVR solenoid / PCM / MAF / VSS / C645 (tranny hardware unit). Which runs behind/below the engine

The only splices on this part of the harness are S59, and S178, but for some reason the service manuals (while giving location diagrams for every component and connector) don't give a location for the splices beyond the text description I quoted. I'm guessing S59 isn't too far from the C3001 connector, since the MAF power comes off that splice, and I suspect S178 is down low to the rear, since the VSS and hardware tranny unit power come off that one.

At least knowing it's north of C120 means I don't have to pull the UIM and look at the injector harness.

I have pulled the PCM connector, and the short to ground remains. I disconnect C3001 and the short goes away, so it's south of C3001. I pull C120, and it remains, so it's north of C120. I was thinking it'd be best to start by looking at the splices, but I may have to just start at C3001 and inspect it all the way. But that "behind/below the engine" is going to be a PITA. I will need to move it off the street if I have to jack her up to examine anything from underneath.

So far the schematic diagrams seems correct as to wire colors matching pin numbers, but they did reverse the relay pin numbers 3 and 5 on the schematic. BTW, I have the actual paper copy of the 98 EVTM, and I'm comparing it to a 97 service CD.

I have a PCM new from a dealer for sale. PM me if you are interested!

It sounds like you are close to finding your problem

Hope it's running before the weekend!

Originally posted by Ex-Mean'Tour:
I have a PCM new from a dealer for sale. PM me if you are interested!

He has already well established that the PCM is not the fault.

Steve