95 EB - Will not start and Scanner cannot run tests

The car will not start after sitting for a week. It had been getting harder
to start after sitting for just a weekend.

The code scanner will not run any tests.
Can I take the PCM out and have that tested?
I have already swiched the PCM/AC relays and this had no impact.
Or what else should I do to diagnose?

Thanks, Bill.

I just checked all of the fuses and these are OK. I have seen this is normally the problem when a scanner cannot test.

Does this mean the PCM is bad?

You should check your battery voltage. If the battery voltage is below 10.5 volts, the PCM may not power up properly. Check the voltage in a couple of places, at the battery posts and at an accessory port or the fuse box.

If the battery voltage reads fine at the posts, but not at the accessory port, your problem may be as simple as loose or corroded battery cables. If the voltage is weak in both places, then you probably have a weak battery and/or a severe drain on the battery.

I would certainly start there before going to the effort of pulling the PCM. Depending on your area, you may or may not have a local shop that can test the PCM.

-Rod

Rod, thanks for the advice about voltage levels. I will check them tonight.

I tested the fuel pressure and at 38 PSI it looks good. I'm still confused why the fuel pump does not shut off after it reachec 38 PSI with the key on. Two remaining issues are:
1. It is getting spark, but for 2/3 coils it is not a steady spark; it appears like it has a pattern for these 2. (Like 3 quick sparks, then 5 with a longer pause inbetween, then repeat). I would expect a constant spark.
2. My code scanner tool cannot read any codes or perform any test. All fuses and relays checked out.

Any other suggestions is greatly appreciated.

Thanks, Bill.

Rod the battery read 12.5 at the battery and 12.2 at the cig lighter.

I pulled aplug after cranking the engine and noticed that the plug was not wet nor did it smell like gasiline.

So something in the fuelrail is clogged( injectors, some other sensor).

Any ideas.

Thanks, Bill.

You may want to swing by your local chain auto parts store and borrow a set of noid lights. These are essentially LEDs that you plug in in place of a fuel injector. The LED should flash during a engine cranking, the flash corresponds to the signal to open the fuel injector. No flash = no pulse for injector.

Knowing if you have injector pulse will help narrow your search.

Have you checked all the fuses, including those under the hood?

-Rod

Rod I have check all fuses incuding the distribution box under the hood and the panel next to the driver's side door. All are OK.

I'll see about getting the noid led to check the injectors. Will I need to dissamble the fuel rail for this, or does this connect through a plug?

Would a dead PCM cause this behaviour, becuase as I mentioned before, the scanner is not reading anything.
Is there some wires I can check for voltage into and out of the PCM to verify it is working?

Thanks, Bill.

You shouldn't need to pull the fuel rail to connect the noid light. The light will plug into the electical connector for the injectors, not the fuel supply.

A dead PCM could cause the behavior, but it's not very common for Ford PCMs to fail. Are you trying to use an OBD-II scan tool to read your PCM? Your 1995 may have an OBD-II like connector, but not actually be the OBD-II protocol, which would explain why an OBD-II reader (if that's what you're using) would not be able to communicate with the PCM.

There will be signal wires you could check with a breakout box or by backprobing connectors, but I don't have the service manual for a 1995 Explorer to tell you which ones to check. You may want to pull up the wiring diagrams from Autozones Repair Info site to see if they have a pinout.

-Rod

Rod, on the top of the PCM it indicates EEC-IV which I believe is OBD-I.

I have been using this scanner for several years now and it has helped with several problems (like bad EGR valve).

I'll try to get the NOID light and perform this test and report back. Thanks for the advice.
I have wiring diagrams from Haynes, but they are difficult to read. I'll try this site.

Thanks, Bill.

Yep, EEC-IV would be OBD-I, and if the scanner has worked on this Explorer before, it does seem like there may be an issue with the PCM or wiring to the PCM.

There was a somewhat similar situation that I read about on the Taurus forum, that one turned out to be a shorted wire in the EEC connector. You may want to carefully inspect the wiring harness for the PCM to see if there are any areas where the harness appears to be damaged.

-Rod

Did you try to jump the STI connector to see if it will flash any engine codes via check engine light ?

http://www.turbotbird.com/techinfo/RetrievingCodes/retrie1.gif


Rod, on the top of the PCM it indicates EEC-IV which I believe is OBD-I.

I have been using this scanner for several years now and it has helped with several problems (like bad EGR valve).

I'll try to get the NOID light and perform this test and report back. Thanks for the advice.
I have wiring diagrams from Haynes, but they are difficult to read. I'll try this site.

Thanks, Bill.

reekor, I did not think to read the codes in that manner becuase I had a scanner. But you have a good idea and I'll try this tonight.

Rod, id did not buy the noid test, but hooked a multimeter to one of the injector plugs. I got very low voltage readings around .03 Volts and it was cycling as the engine was cranked. This seems really low, do you agree.

Someone also suggested I take some other readings:
1. IAT (internal air temp) resistance check was valid at 31K olms which is what is should be for 70 degs outside.
2. Mass Air Flow positive to neg pin read 5.7 volts. My manual says it should read around 10. Does this mean anything to anyone.


The PCM cabel is in good shape, no worn spots. I also removed the PCM plug and the connections all look very clean, an no corrosion. I may have a bad connection, but don't know how to go about finding it.

I really want to put in a new PCM to see if this helps. (any thoughts?) If I can find a place that will let me return it I will.

Thanks for the help and please keep the ideas coming.

Yeah, good idea reekor, very good idea.

It's really hard to tell if the injectors are getting a good pulse using a multimeter. The pulse width is so short, the meter may not respond quickly enough to give you an accurate reading. Did the store not have a Loan-A-Tool program that would let you borrow a noid light kit?

I'm not sure what reference voltage the MAF should use, but I would suspect a 5V reference rather than a 10V reference. Even then, the voltage seems a bit off.

-Rod

reekor, I did not think to read the codes in that manner becuase I had a scanner. But you have a good idea and I'll try this tonight.

Rod, id did not buy the noid test, but hooked a multimeter to one of the injector plugs. I got very low voltage readings around .03 Volts and it was cycling as the engine was cranked. This seems really low, do you agree.

Someone also suggested I take some other readings:
1. IAT (internal air temp) resistance check was valid at 31K olms which is what is should be for 70 degs outside.
2. Mass Air Flow positive to neg pin read 5.7 volts. My manual says it should read around 10. Does this mean anything to anyone.


The PCM cabel is in good shape, no worn spots. I also removed the PCM plug and the connections all look very clean, an no corrosion. I may have a bad connection, but don't know how to go about finding it.

I really want to put in a new PCM to see if this helps. (any thoughts?) If I can find a place that will let me return it I will.

Thanks for the help and please keep the ideas coming.

Rod, the noid light was not available for load but another store had a noid light kit for $20. I agree with your point that pulse width may be too short to accurately detect voltage. I may just buy it, but first I want to check the CKP.

A girl working at the the auto store said her 97 Explorer quit starting and that was her problem.

She said the policy would not allow me to return a CMP if I purchased and installed it. She did recommend me removing mine and look for obvious burn marks or damager. Not a guarantee test of the PCM but worth a try.

I'll try these two tonight.

Thanks, Bill.

With the CKP connector removed, voltage to the CKP was correct at 1.5 V.
And while cranking the engine the voltmeter did register changes in current when connected to the CKP leads.

I looked at the PCM. Everthing looked good (pins, no discoloration) (I didn't think this would help anyway, but I got the PCM part number if I need it).

I'm running out of thinkgs to test. I'm almost ready to tow it to a dealer to atleast diagnose unless there are more suggestions.

Thanks, Bill.

Did you try reekor's suggestion of checking for codes with the shorting wire?

Depending on your patience, you may want to download the factory service manual (www.fordcds.com) and get the PCM pinouts, then check for the appropriate supply and reference voltages.

-Rod

Rod, I did try reekor suggestion of connecting the two plugs with a jumper wire, then putting a meter between the +term and the specified pin. I got a voltage difference of around 12 volts, but nothing else happened on the meter or with the check engine light.

I'll see if I can find the pin layouts for the pcm.
Bill.

That does sound suspicious....

-Rod

Towed to a dealer service center.
After 2.5 hours of diagnostics, still could not determine why it is not starting or PCM is not responding.
They are going to replace the PCM (but have promised not to charge me for it if the PCM is not bad).
I think it is ridiculous that they even the dealer cannot test the existing PCM to know for sure if it is defective.

Be sure to keep us informed of progress, I'm pretty curious on this one.

It was a nice gesture of the dealership to not charge you for the PCM if that doesn't fix it.

-Rod

Rod, I agree it was nice, but I think they should have a way to diagnose the board anyway. Think of how much of my and their time (which I am paying for so it's my time) it would save. The board supports a defined interface so they should be able to pull, it connect it and diagnose.

Anyway, I will keep you informed.

I am happy to report the PCM did start the car today when I went to pick it up, but nothing on the AC panel was working, not the vent or anything.
I went back inside. A mechanic drove it off and after 1/2 hour they tried to charge me $700 to fix it! They said it was the AC control unit board. I was not happy and let them know. The AC/Heater/Vent was in perfect working order when I brought it in. They must have done something, pulled a cable, or pushed current on the wrong wire, or just the PCM starting up?

Their second choice was no labor charge $500. Still I persisted. Then they offered the part at cost, no labor $351. At this point I requested the part number and was going to drive off un-happy, but going to price it somewhere else. This is when he offered to just fix it. So tomorrow or the next day it should be fixed.

What does everyone think? How could they have damaged this part?

Does your Explorer have the Automatic temperature control unit, or manual controls? If manual, there is no control unit board, so I suspect the electronic. If absolutely nothing worked, that unit should be fuse protected, so I'd start there. If the fuse was fine and there is power to the controller, I'd be more than happy to tear it apart and let you know what it appears happened (ie: their mistake or just coincidence).

-Rod

Rod, it has Automatic temp control.

They put a new unit in so I don't have access to it. They had no interest in diagnosing the unit themselves. I wish I could get a hold of it so understand what happened. Maybe they did open it up and that is why they fixed it. The new unit looks completely different, probably for a different car, but I do not car. Everything works including the Rear Fan control.

So my car is back with a new PCM running. I want to look under the hood closely at everything they checked. I also want to run my scan tool against the new PCM.

Thanks, Bill.

Glad to hear another Explorer is back on the road. From my limited experience, Ford PCM failure if pretty uncommon (compared to GM anyway), but I'm sure it happens.

-Rod