1998 Ford Explorer 5.0 Engine Diagram

What do you mean by that you attempted to check all grounds connections without success?

While I am not certain of it, I am assuming there is constant 12V to the injector and the PCM grounds them to turn them on. It might help to find a wiring diagram for that.

IF that is how it is set up, when the injectors shouldn't be on, for example when the key is in aux power on state but engine isn't running, a multimeter should not measure continuity to ground through the lead going from each injector to the PCM.

You should notice a difference in resistance reading on that wire for each injector that stays on, compared to the two injectors that don't stay on which should be an open circuit multimeter reading or at least a pretty high resistance if there is some loop that would let a little current leak.

If you find that there is continuity to ground when the injectors shouldn't be on, trace that wire to the PCM, moving it around a bit to see if there might be some break in the insulation shorting it, measuring for continuity to ground as you move it around.

I don't know if the wiring harness connector to the PCM allows extracting individual pins easily or at least without damage. Usually there is a way to get connector pins out if you have the equivalent of locksmith or dentistry tools and know where a friction tab on the pin is that locks it into the connector.

Anyway if you can extract the individual pins for each injector, you can measure continuity between the PCM mating pin and ground with the rest of the electrical system still plugged into the PCM.

It would help a lot to have the wiring diagram and/or schematic, though usually Ford so-called diagrams are sort of a bastardization of the two combined instead of proper electronic symbols, but at least it would beat having nothing.

Then again, if the wire is continuous from injectors to PCM, you can note the main color and stripe color and measure continuity between the injector plug and the PCM plug to determine if it's the same wire, except if the PCM is grounding out multiple plugs then all those grounded may read having continuity.

Regardless another thing you could do is unplug the PCM connector then measure between the injector pin that gets grounded and ground to see if it is shorting out to ground without being plugged into the PCM.

It just seems odd that so many, yet not all are constantly on. Is there any chance the vehicle was hooked up to a high power battery charger that might have overvolted the system? Some of the older ones may reach 17V or higher which can cause damage.

I have a '98 but with the 4.0L not 5L, so I cannot verify anything on my vehicle with certainly if/when it can't be assumed to be the same.

Oh, I assume you have no OBDII diagnostic codes?

Source: https://www.explorertalk.com/threads/1998-explorer-5-0-liter-4x4-fuel-injectors-stuck-on.47080/

Posted by: delilahriester.blogspot.com