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Ford Explorer Maintenance - Modifications - Performance Upgrades - Problem Solving - Off-Road - Street
Explorer Forum Covers the Explorer ST, Explorer Sport, Explorer Sport Trac, Lincoln Aviator, Mercury Mountaineer, Mazda Navajo, Ford Ranger, Mazda Pickups, and the Ford Aerostar
I won't say there's no chance. The way I like to diagnose DC circuits is to start at the battery and note voltage (it might be time to buy/borrow a cheap battery charger so you can get your battery charged up for this). Then move to the next convenient point in the circuit and see what the voltage is. Continue down the circuit until the voltage drops. Where the voltage drop is usually where the problem is. In your case, assuming there's 12 V at the battery, you're meter is indicating a 4V drop between the battery and the fuse, which suggests to me that the problem is in between those two points.
Im not to good at reading wiring diagrams, so how should i diagnose this problem. I was thinking following he wire from the fuel pump fuse to the battery but would be easier probly if i knew what wire it was and were it connects to power. Im trying to figure out what happened but can understand why all of a sudden while driving it just shuts off mostly when full throttle. I have also noticed the battery seems to be getting drained faster, and when i turn the light on the battery gauge turns to about straight up and down.
Ok well ive been researching some threads on here and was wondering is the brown relay pictured above the fuel pump relay? I took the jimmy rigged relay pictured off and it didnt affect the starting, but when i unplugged the brown relay no engine light or brake light came on when i turned the key. There should be three relays.
Cars are becoming more electrically intense, not less. IMO, this is a good skill to develop if you are serious about doing your own work.
I was thinking following he wire from the fuel pump fuse to the battery but would be easier probly if i knew what wire it was and were it connects to power.
From the wiring diagram for my '92, there's a black wire that feeds power to the power distribution box (PDB), which then branches to each of the fuses. The PDB is the box that is supposed to contain those main fuses and the relays (as you noted there should be three). On my '92, the PDB has two "levels:" the top level has the fuses. This top level lifts off to reveal the relays. I don't remember what color Ford used for the AC relay, but the brown relay (if Ford original) would be the main PCM relay (this seems confirmed when the CEL didn't come on when this was disconnected), and the fuel pump relay (again only if Ford original) would be green. Are you able to locate the other two relays?
that black relay, if it's the ford original may be the wide open throttle relay, which is in my understanding used to shut off the a/c clutch at WOT in the interest of reducing the load on the engine for passing and hill climbing. As you said there should be three relays there in the power dist. box, pcm, fuel pump, and wot fords factory installed relays were brown, green, and black, respectively. My 91's been giving me lots of electrical problems lately too so you can at least have the comfort of strength in numbers. We'll whip those dirty old gremlins into shape one way or another
You were most likely onto something with your volt drops, Check all the connectors in the circut for the fuel system for heavy corossion. If you are losing that much voltage the motor will be weak or not run at all, causing your issues. Find your Fuel pump relay and check the connectors for damage. You may be doing the same repair that was done to your WOT.
You never want to see more than 1 volt drop across any connection. Best case is 0-.2 volts, .5 is acceptable but may be a warning. Remember as the voltage drops the amperage rises and damage is more likely to the circut.
Jeffpcell is right. The relay you were asking about looks to be the WOT relay based on the color wires you described. It cuts the A/C compressor when at full throttle. The relays are located WOT in front, PCM, and fuel pump in the rear. The green orange wires that are cut are for the AC clutch circut. One goes to the Clutch cycling pressure switch near the evap core pipes and the other comes from pin 10 of the PCM. Unless you want your AC to work don't worry about these.
I think you may have issues in the whole power dist box. Look at the underside and make sure its not burnt up or badly corroded.
well i got it figured out. I changed the fuel pump fuse, which was hiding under blower motor. lol but now it will run, but has a bad idle surge and when it does the check engine and battery light come on. Could it be a bad battery or alternator?
Yes. Some parts stores have the ability to bench test batteries and alternators, it might be worth the effort to pull them out and take them in for testing. I might also pull codes again to see what problem the computer is seeing now that you've got it to start.
Check charging voltage at the battery terminals. You want about 13.5 to 14.5 volts at idle. The battery should hold about 12.7 volts and not drop below about 10.5 to 11 volts while cranking the motor.
