1998 4.0 OHV Explorer won't start

[Rob&Robby]

It had been running fine. My son cranked it up today, and a few seconds later, it shut off by itself and wouldn't start again..... I checked it for spark by pulling off one of the spark plug boots and doing the old screwdriver trick.... No spark. I had a friend, who seems very mechanically inclined come check it out. He did some tests with my voltmeter and the coil pack, and according to him, the coil pack is good, but not getting any power. After some searching on the internet, he suggested I change the Crankshaft Position Sensor (CKP), so we did.... Still same issue. No spark. I purchased a Haynes manual for it, and have been doing some reading. At this point, everything seems to be pointing to the Powertrain Control Module (PCM / EEC-V). Does that control whether or not the car gets spark? Could it be the relay? How do you test the PCM and/or the relay? Everything else works. Car turns over, lights, accessories, etc.... Just won't start. What else might it be, or what else should I look at???

Thanks
Rob

 

[Rob&Robby]

Upon further investigation, it appears to be a bad coil pack.... After reading through the manual, I decided to go check the coil pack myself with all my new found information. As per the Haynes manual, the primary resistance should be between .3 and 1.0 (mine is 2.5) and the secondary resistance should be between 6.5 and 11.5 (mine doesn't even register).

However, I did notice that only 1.39 volts are going into the coil pack from the connector plug with the ignition on, not running. Coincidentally that is the same voltage going into what I assume is a fuse (diode, the size of a mini fuse), located right beside the PCM relay inside the Power Distribution Box. Is that voltage correct, or could there be another problem that caused the coil pack to fail? Should the coil pack be getting 12 volts, or does the coil pack increase the voltage itself once the car is running?

Also, any ideas on testing the PCM and it's relay?

 

[Rob&Robby]

I did some more reading in the manual, and on here last night and performed some more tests..... There is a very good thread on "Engine No Start Procedure". After reading it, I went back to the car and one of the first things to look for is if the PCM is getting power by seeing if the Check Engine light comes on when you turn the key to ON.... Mine doesn't. I know the bulb works because my check engine light was on before. I had a 98 Expedition once before and the check engine light was always on, and it ran fine. I had it checked out many times, and they never could find anything, so I didn't pay too much attention to it. At any rate, I know the bulb works. So this, according to the thread, tells me my PCM is not getting power. And according to my other test, my coil pack is bad too. This sound familiar to anyone? Any insight on any of my questions???

Thanks

 

[2000StreetRod]

No check engine light

I suspect that your ignition coil pack may be good and that your PCM is just not getting power. Did you perform my PCM Power Procedure?

I originally wrote it for my 2000 Sport and then added the differences for the 1996 year. There were significant wiring changes to the Explorer in 1998 so yours should be very similar to my 2000. You probably have a bad relay or a blown fuse. If a fuse is blown you should try to determine why it blew.

 

[Rob&Robby]

I had been messing around with the power door lock switch on the drivers side, which also doesn't work... Not getting power either. I tried to jump it from the main power lead to the window circuit. Maybe that did something. I will check it when I get home.

I printed all of your Engine No Start steps.... Thanks so much for taking the time to do all that. It will all be very helpful. I just bought the owners manual on ebay. Should be here in about a week.

 

[2000StreetRod]

Owners Guide online

You can download a copy by using the following link, clicking on Owner Guides and answering the questions:
http://www.motorcraftservice.com/vdirs/retail/default.asp?pageid=&gutsid=

 

[Rob&Robby]

Good news and bad news...........


The good news is, it's running again....

The bad news is, I have no idea what the problem was. The PCM was definately not getting power. (no check engine light when key in ON position). I pulled out a couple fuses to check them (they were fine), even stuck the probes into the fuse panel itself (left side of dash panel, inside the vehicle) and no power to PCM, charged the battery (which was fine before, but wore down a little from all the trying).... At one point I happened to look at the dash, and there was my little friend. The check engine light. I threw the coil pack back on, which according to my test, and manual specs, was bad..... hooked the plug wires back on it, and it cranked right up. I love that it is running now, but hate not knowing what the problem was for future reference....


One thing I do know about these vehicles is that the PATS is not my friend. Any way to bypass it???

 

[2000StreetRod]

Congratulations!

Good news and bad news...........


The good news is, it's running again....

The bad news is, I have no idea what the problem was. The PCM was definately not getting power. (no check engine light when key in ON position). I pulled out a couple fuses to check them (they were fine), even stuck the probes into the fuse panel itself (left side of dash panel, inside the vehicle) and no power to PCM, charged the battery (which was fine before, but wore down a little from all the trying).... At one point I happened to look at the dash, and there was my little friend. The check engine light. I threw the coil pack back on, which according to my test, and manual specs, was bad..... hooked the plug wires back on it, and it cranked right up. I love that it is running now, but hate not knowing what the problem was for future reference....


One thing I do know about these vehicles is that the PATS is not my friend. Any way to bypass it???

Glad that it's back to running. If PATS were easy to defeat then it wouldn't be a theft deterrent.