Odd issue with my 1994

[97RangerXLT]

I love it when a plan comes together...

hey, thats my avatar's line!

AJ

 

[RobbieD]

Good job! Our "caps" are off to you, Sir!

 

[scotts90ranger]

Sounds like that was your whole problem... the engine computers I'm used to are sealed units (you CAN get them open, but they weren't designed to be, but everything is potted and more complicated than just capacitors and resistors) so that isn't an option and they are at most 16 years old so not worn that way yet.

That $10 saved a couple hundred, it helps being handy!

 

[RonD]

This computer just had 2 screws(torx) one on each side, and top and bottom covers came off

Both sides of the circuit board did have a coating to seal them, what I saw as "overspray", lol
But soldering iron melted it
I did a dab of glue on each solder point on the back side, to reseal them, but I doubt that was needed at this point, would like to get another 10 years out of it, but....................not likely
There are some 1984 Rangers around but they are few and far between

 

[RobbieD]

While we're on this subject, does anybody know of a GOOD source for replacement ECMs for older Rangers? Or, even better, a specialist repair shop that you can ship your computer to for a quality diagnosis and repair?

I have seen "reman" ECMs from the usual high-volume sources like RockAuto, but I'm thinking of a more specialist ECM rebuilder, that knows the unit and has the right parts and test equipment. If such a company exists, it would be nice to know about it.

 

[RonD]

I wouldn't think there would be just because of the cost of a "reman" computer, $150-$250

Labor is expensive, and to test components at board level is time consuming, you could easily spend $1,000 and not find the problem
Computer is also not a "visible part" so no value in an "original equipment" restoration

This site: http://www.auto-diagnostics.info/ford_eec_iv

Does have links to EEC-IV technical specs, like this page: http://www.auto-diagnostics.info/pdf/ford_eectec10.pdf

 

[RobbieD]

Good points. I've yet to have an ECM go bad, but one day I'm sure I will. I plan on driving my old trucks until I'm too old and can't drive. Yes, $150~$250 is not that bad, but across the board these days, replacement parts' quality has, in general, gone to hell. At least, capacitor failure seems the most common problem in these, and are not that hard to replace.

 

[Alan_nc]

I've had to put the jumper across the fuel pump relay (with a switch) to make mine run. I'm pretty sure something is fried on the computer. I can't get the computer signal that tells the fuel pump to run for 2 sec prior to turning the key all the way to start. Runs fine this way but I do not have the safety of having the fuel pump automatically shut off when the key is off. Not worth $150 + to get this problem fixed.

This isn't really a big problem but I may be headed for bigger problems if the computer is starting to go.

 

[RonD]

I've had to put the jumper across the fuel pump relay (with a switch) to make mine run. I'm pretty sure something is fried on the computer. I can't get the computer signal that tells the fuel pump to run for 2 sec prior to turning the key all the way to start. Runs fine this way but I do not have the safety of having the fuel pump automatically shut off when the key is off. Not worth $150 + to get this problem fixed.

This isn't really a big problem but I may be headed for bigger problems if the computer is starting to go.

You can do a jumper on the OBD1 connector instead, and fuel pump will come on and go off with key on and off

Look here: https://www.therangerstation.com/tech_library/OBD_I.shtml

You can see the OBD connector and the Fuel Pump Slot labelled
That slot has the computers Ground for fuel pump relay(pin 22) and then a wire from OBD connector to the fuel pump relay's ground pin

Put the fuel pump relay back in, and turn on the key
Then Ground that slot, the fuel pump relay should "click" ON and fuel pump should start
Turn off key and fuel pump will stop running

If grounding that slot does NOT turn on fuel pump relay(key ON), then you have a wiring problem not a computer problem
But test if computer is grounding that slot first, put a test light in that slot and to Battery Positive, turn on key
If test light(or volt meter) comes on(for 2 seconds) and then goes off computer is grounding that slot
Then, with key still on, use voltage meter(or test light) from that slot to Ground, should see 12volts coming from the fuel pump relay, if no 12v(key on) then that wire from OBD slot to the fuel pump relay is bad/broken

 

[Alan_nc]

O.K. I'll try to wrap my head around this. It's a bit above my "right & need to know level". I'll print this off and carry it out to the truck and see if I understand it while I'm looking at the parts.

 

[RonD]

Wiring to Ground and power fuel pump(FP) relay is like this

Computer(pin 22)--------------------OBD connector------------------fuel pump relay's coil------------12v(from EEC relay)

When you turn on the key the EEC(PCM) relay closes and powers computer(EEC), injectors and fuel pump relay's coil

So with key on FP relay's coil has 12v but no ground, computer would normally ground it for 2 second on boot up
But the 12volts should be there with key on
A relay's coil is just that, a coil of wire, so the 12v passes thru it to OBD FP slot, so you can test for 12v there
And should see 12v with key on

If you ground that slot, its not a Short because the relay's Coil is there, same as a light bulb is not a short if connected to 12v and ground, because the light bulbs "coil"/filament is there, between the 12v and ground

 

[PetroleumJunkie412]

While we're on this subject, does anybody know of a GOOD source for replacement ECMs for older Rangers? Or, even better, a specialist repair shop that you can ship your computer to for a quality diagnosis and repair?

I have seen "reman" ECMs from the usual high-volume sources like RockAuto, but I'm thinking of a more specialist ECM rebuilder, that knows the unit and has the right parts and test equipment. If such a company exists, it would be nice to know about it.

.....sup.