I have an 86 2.9L A4ld 2 wd Ranger, One day all was running fine i had just put in a deep cycle starting trojan battery (for the system) the weekend before. Just then it all died in the lot after driving around for a few days. It seemed like a dead battery but i tested it and it was fine. So then i replaced the starter solenoid. This brought back the basic electrics, head lights, interior lights, it will crank over but not start now, i've tested the wiring to the coil and out, its all fine. I'm pulling the codes tonight, Is it the computer? or maybe some $#@% sensor? it seems fine there is good spark, fuel is going through, it wants to fire but just wont!

 

You can read the codes in the computer and see if all is well. Here's how to do it.

http://www.dalidesign.com/hbook/eectest.html#TOP

 

well, i tried to pull them but the reader wouldnt start to blink, it just stayed on. I measured the voltage at different points anf found none across the fuel pump whith the ignition on the run pos. none across the inertia switch, so i measured the voltage to the ecc and found a 11.98 into it but none coming out on any circut....is it the ecc? i dont want to have to pay for a diagnostic but i might not have any choice. i need this bitch for work soon.

 

You should be able to get the computer to talk to you. Double check your hook-up on the diagnostic connector, and if it still will not give out any codes, one other thing you can check is a ground over by the battery.

I don't know about the rangers, but the F150's had a small ground wire attached to the negative of the battery. This ground sometimes has a connector in it that can corroded and break in two. It is an important ground for the computer. I don't know if your truck has this ground, but look over there in the battery area and see if you have any problems with any small ground wires.

 

the ground is there, from what ive read its a ground for the eec module, i measured the resistance across the connector and it was fine... the reader is a cheap $30 deal, could it be the reader? its brand new... Ive heard that the eec relay might cause somthing like this, im planning to recheck the eec ground, and replace both the fuel pump relay and the eec relay.

 

The EEC relay does feed the stuff on the engine that goes to the computer. But the computer still has a direct 12v line coming into it, so I still don't know why it won't give any codes.

 

thats why im wondering if the eec has a short in it. the hard line has 11.98v to it. thats whats confusing me. Maybe its completly fried?...

 

well, i found that the fuel pump relay has no power to it, as well i checked all of the connections to the eec, only power on the 12v direct line, i talked to my mechanic, he said that this is usually what happens when there is a voltage spike that kills the eec. i have a decent system so i wouldnt be surprised. im replacing the fuel pump relay and the eec today, as well im going to check the fuseable links on the fuel pump relay...not much else i can think about doing.

 

Don't know about Rangers, but on Aerostars if you have a CEL and can't read the codes then the EEC may be in HLOS mode (hardware limited operation mode).

Just a thought

Ron

 

well, changed the fuel pump relay its still not getting any power, changed the eec still cant read the codes, the eec relay is working fine, now im wondering if its maybe the power distribution box, does anybody know where this and the associated fuses are? the fuel pumps arent getting any power so im wondering if its somthing just this simple?

 

Wait a minute. Let's stop and do a little bit of testing. Here's a pretty good diagram of your truck's wiring at the location you are looking at.
http://www.autozone.com/images/cds/g...3d800f9472.gif

Go get a voltmeter or testlight, and let's do some testing.

The battery is sort-of in the middle top portion of the diagram. Follow the red wire out of the +. Follow it down and to the right. Go around that little square bend and you will end up at a fusible link "L". Go straight down on the yellow wire and it goes into the EEC relay. Go out to the truck and make sure you have power on the yellow wire going to the eec relay.

To explain a little bit of how it works, you will see coming out of the EEC relay there is a red/lightgreen. If you follow that over to the left and then up, you will see that it goes to the ignition switch. As soon as you turn the key on, power is sent to the eec relay coil, and it clicks in, making the connection on the yellow wire going to the eec relay. If you follow the blk/lightgreen wire coming out of the relay, you will see that it is the - or ground return.

Coming out of the eec relay, a red wire feeds another fusible link(another place to check for a burn out) and then goes to all the computer stuff like injectors, solenoids, etc. How it works is the eec relay feeds 12 volts all the time to the computer components, and to make the component come on, the computer grounds the other side of the component, making it come on. So for instance, all the injectors have 12 volts all the time, as long as the eec relay is pulled in. When the computer wants a certain injector to come on, it grounds that injector wire going to the computer terminal to fire it.

Let's look at the fuel pump relay. It works basically the same as the eec relay, except the computer grounds the tan/ltgreen wire to make it come on. You need to check for power on the yellow wire again, and it you can see it is fed by different fusible links(more stuff to burn out). If the fuel pump relay kicks in, it will send power from the yellow to the orange/lightblue, and on to the fuel pump safety switch and then the fuel pump itself. So as you can see, if the computer is not working, it will not ground out the tan/lightgreen wire coming out of the fuel pump relay, so the fuel pump will never come on if the computer is not working right.

You can see the pin #5 is the power terminal for the computer. #49 is ground.

 

well, was a faulty fuseable link, took a while to track as it had been replaced before, (L) to be specific. as well, there was a rub through on the wire further down, had to take out all of the looming to find it (as well as the previous owners ****ty electrical tape job... Thanks Franklin that wiring diagram was WAY more accurate than the one in my Haynes book...

Cheers to everybidy for their help!