A problem with the EEC module fuse in 95 tour

[fastasshell]

Hi I have a 1995 contour 2.5 SE 5 speed and the EEC fuse keeps blowing. The other day i was driving it and it bucked once and then it died. Now i was pretty far away from home when this happend and i had my daughter with me and i was not walking home with her. So i did the next best thing. I riged a jump wire in that fuse. And it got us home. Rough but we made it. Now what sould i look for? A buddy at the local parts store said that he would change the EEC module/Computer/Brain Box. what ever they call it. Anyways please get back at me when ever you have the time. I will appreciate it very much! Thanx

[fastasshell]

anyone out there have a similar problem? I know that 1995 contours has bad wiringharness in them. need help please!!

[fastasshell]

please somebody help me out!

[Selectron]

The problem is listed in the contour.org FAQ section, but there's no advice on how to deal with it. I'm not familiar with your vehicle by the way, but I'm an electronics engineer so I'll tell you how I would set about finding the intermittent short-circuit (and note that intermittent faults are always the most difficult to locate).

That brief article links to the vehicle recall instructions. At the top of the page are some tables, followed by a flowchart, and then beneath those are a series of diagrams which illustrate the possible problem areas - as you will see, there are many of them. Notice that those diagrams only show you how to check the harness in the areas where it is accessible - it then goes on to describe how to use test gear to check for faults in areas where the harness is physically inaccessible, or taped over to the extent that visual inspection is not possible.

I'd take a blown fuse (it has to be blown - won't work with a good fuse), cut or file the corners off of it and then solder a 12V lamp onto it, using at least a couple of metres of wire so it would reach to under the hood - see diagram below. I'd use a lamp of around 10W or less - an interior courtesy lamp bulb would do, or a tail-light bulb - the exact wattage isn't critical. After soldering, wrap some insulating tape around the metal parts of the bulb, so they won't short-circuit against anything.

Check first to verify that your test lamp works, by connecting it to a 12V source, then insert it into the EEC fuse socket (it won't illuminate yet - it only lights up in the presence of a short-circuit), switch the ignition on (but don't start the engine) and take the lamp around to under the hood. Then very gently move the wiring harness in the suspect areas, as indicated in the Recall diagrams - when you move the portion of harness which is faulty, and cause a short-circuit, the lamp will illuminate.

The risk that you run in doing that, is that you might make it worse, depending on how fragile the cracked/damaged insulation is, so that's why I said to only move things very gently. With luck, you will be able to identify the problem section and then come up with a plan to deal with it.

This one could be a real headache to trace, and then to repair, and I'll repeat that you do run the risk of causing the intermittent short-circuit to be become a permanent short, so you'll have to decide if you want to take that risk. I don't see any other way to do it though.

And this is the test lamp which would be required. Any comments from Contour owners who've had to deal with this?

[fastasshell]

Thanks for your feed back I will try this light bulb trick. At this point i am willing to try anything. I will post after i try this to let you know how it went.

[fastasshell]

Ok this is what i came up with. I pluged the lightbulb/fuse into the EEc fuse inlet and when i turn the key the light comes on and i figured this would happen. But i noticed that the light came on right after my fuel pump engaged. Now would my fuel pump have anything to do with it. And stupid question but what dose the EEc actualy go to. is this my computer management system. The reason i ask is because the parts store said that it could be the computer. I dont know i figured they just wanted to sale me a part. Anyways this is what i got for now. And thanks for your advice.

[fastasshell]

Ok in detail this is everything i did to the car. after the car was sold to me i notice that the wiring look like hell so i just drove it. Now two weeks after having the car it started to buck and lertch so i took out the wiring harness thats under the intake and patched it up by puting heatshrink on all the wires that needed it. put the car back together the car ran fine for months. Now to the EEC fuse problem that i am having.I took the wiring harness out thats on the driver side finder weld and this was an adventure let me tell you. it goes to the dual fans the fuse box under the hood the ac /headlights / markerlights /dual horns/foglights/windsheild washer tank anyway pretty much everythying and i had it out for about a week and i also heatshrinked all the wirers that needed to be on that wiring harness.BUT when i took that wiring harness out i noticed that some wires were touching coming from the dual fans. Now i wonder if i used a new fuse and unpluged the fans one at a time to see if one of them have a short that would blow that fuse out. just an idea. Please let me know if this sounds like a good idea or if its just a waste of time. And thanks for taking the time to help me on this.

[Selectron]

I should have explained about the test lamp in greater detail. With the test lamp plugged in and the ignition switched off, there should be no significant current flow, and the lamp should be off. When the ignition is switched on, the EEC fuse socket supplies current to several devices - however, instead of flowing through the fuse filament it will now flow through the filament of the test-lamp bulb instead - this will cause the lamp to illuminate somewhat, depending on how much current is flowing. However, it should light at a much-reduced intensity and will only light at full brightness when it has a direct path to ground, which is to say, when a short-circuit is present - that is how to identify the short-circuit condition.

Regarding the fuse - I've looked at diagrams from three sources and none show an EEC fuse, but I think we're talking about fuse # 9, rated at 20 amps and located in the engine compartment fuse box - is that correct? It's shown on my diagrams as the 'PCM' fuse, which powers the PCM and several other devices. I'll take a closer look at the diagrams and list them, if that's correct.

[fastasshell]

Correct it is fuse # 9 Thats the one.

[Selectron]

Some further information - I'll make three separate posts, to make it easier to follow.

First, a list of the items fed via the EEC fuse:

• PCM Power Relay switched contacts (located in engine compartment fuse box)
• A/C WOT Relay (hot end of coil circuit - ground side switched via PCM)
• Low Speed Cooling Fan Relay (hot end of coil circuit) (switched side fed via 60A Cooling Fan fuse)
• High Speed Cooling Fan Relay (hot end of coil circuit) (switched side fed via 60A Cooling Fan fuse)
• Evaporative Emission Canister Purge Valve (hot end of coil circuit - ground side switched via PCM)
• Mass Air Flow Sensor (other side has two feeds into PCM, plus one to ground)
• Powertrain Control Module (power feed - there are several of these, feeding different pins on PCM)
• Fuel Injectors (hot end - ground side switched via PCM)
• Idle Air Control Valve (hot end - ground side switched via PCM)
• Intake Manifold Runner Control Solenoid (hot end - ground side switched via PCM)
• EGR Solenoid (hot end - ground side switched via PCM)
• HO2S Fuse 15A (to Heated Oxygen Sensor Relay & Heated Oxygen Sensor)
• Fuel Pump Relay (hot end of coil circuit - ground side switched via PCM)
• Ignition Control Module (module main power feed)
• Vehicle Speed Sensor (might not be fitted to manual transmission?)

[Selectron]

Just to clarify what the 'EEC' actually is - it's the Electronic Engine Control system, but there is no such thing as an 'EEC module' in your car. 'EEC' refers to the overall system, and that system comprises the Powertrain Control Module (PCM), plus its associated sensors, control valves, solenoids, the Ignition Control Module, fuel injectors, etc. As you can see from the list above, they are all fed from fuse #9, so that will be why they refer to it as the 'EEC fuse'.

As you can also see from the list above, the PCM is only one item on a long list, so there's no particular reason to believe that it is responsible for blowing the fuse, and therefore no reason to believe that replacing it would cure the problem - especially not when we already know that the wiring harness insulation on your model is known to have a design fault and is very prone to insulation failure, causing short-circuit faults such as you have - your particular fault being of course an intermittent one.

[Selectron]

You mentioned bare wires at the cooling fans. There are two sides to the cooling fan circuit - the relay coil side, and the switched contact side. The relay coil circuits (High and Low speed) are fed via the EEC fuse, and controlled by the PCM. When the coil is energised, the switched contacts close, and feed current via the 60 amp cooling fan fuse to the fans. The wiring for the relay coils, powered via the EEC fuse, is unlikely to go anywhere near the actual fans, so bare wires and a short-circuit in the vicinity of the fans would be more likely to blow the 60A cooling fan fuse, but wouldn't be likely to affect the EEC fuse. Therefore I don't think there's anything to be gained by doing the fan test that you suggested. Plus of course, you don't actually have a short-circuit right now, because it's only an intermittent short, so it's unlikely that either fuse would blow anyway.

I'd continue with using the test lamp to check for shorts in the wiring harness. As you've discovered, the lamp illuminates when the ignition is switched on, but that should be at much-reduced intensity. When checking the harness, and physically moving it, if you cause the short-circuit to occur then the lamp should come on at full brightness, and that's how to tell when you have located the short.

Regarding the fuel pump - I think that should only come on for a couple of seconds when the ignition is switched on, as it primes the fuel delivery system, and should then switch off. If it stays on, then that would be because it can't build sufficient fuel pressure, because of the current-limiting effect of the test-lamp bulb filament. The way around that would be to temporarily remove the fuel pump fuse - fuse #14, 15 amps, located in the engine compartment fuse box - and then continue with the harness testing.

Because there are so many items fed from the EEC fuse, the intermittent short-circuit could be in many different locations. If it was a constant short-circuit then it would be so much easier to locate, but because it's intermittent, the best chance that you have of locating it is by using the test lamp. Let me know if you don't follow any of that.

[fastasshell]

No that all makes sense. thanks i will try the test and tell you how it all went. (Man this is going to be a mess.)

[Selectron]

Yep, this could be a major headache just trying to locate the fault before you even get started on repairing it.

Just another thought on locating the short-circuit. If the test lamp is illuminating brightly enough to make it difficult to differentiate between normal current flow in the circuit, and a short-circuit, then you could use a multimeter instead. This would be the method:

• With the ignition switched off, remove the PCM relay from the engine compartment fuse box.
  
• There should be markings on the base of the relay to identify its terminals, which should be: 85, 86, 30, 87, and possibly also an 87a
  
• Leave the relay unplugged, and ignition off (it doesn't matter whether the EEC fuse is inserted or not) and connect the meter's red probe into the (now empty) socket for terminal 87 in the fuse panel.
  
• Set meter to lowest resistance range.
  
• Connect meter black lead to a good ground point.
  
• Move the suspect sections of the harness, whilst looking for the meter resistance reading to drop to zero ohms - that would indicate that a short-circuit was present.

Many meters have a continuity beeper on the lowest resistance range, which isn't a great indicator of continuity by the way because some of them beep even for a resistance of some tens of ohms. If your intermittent short is capable of blowing a 20A fuse then it's dead short-circuit to ground, so you'd have to ignore the beeper and look instead at the display digits. Oh and before you start, touch the meter probes to each other to check what your display indicates for a dead-short - that will probably be around 0.5 ohms, so that is the reading which you would be looking for when a short-circuit was present.

The test-lamp is the easier option, but you do have the choice of using a meter too.

[fastasshell]

yes i will try the meter on it as well as the light bullb. thanks for laying the steps out for me to follow i will use them.