91 Exp just died.. turns over, plenty of power, put gas in, doesn't start | Page 2 | Ford Explorer Forums - Serious Explorations

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91 Exp just died.. turns over, plenty of power, put gas in, doesn't start

Looking at this further the A/C WOT cutoff relay is the A/C Wide Open Throttle Cutoff relay....???? hmmm not sure where that is but perhaps under the dash some where. .... or perhaps the MAP sensor is toaste ... also possible as it also appears to get its feed from the ECC relay.

Lastly, other areas to poke around. The same power feed point also goes to your injectors (hard to believe they have a problem... but maybe burnt wiring on the way there... check these visually) and also the purge canister solenoid (??) needs to be check much the same as you checked the other relays although there is likely to be only two leads which are for the solenoid. I notice further that there is also a converter clutch solenoid also that receives it feed from the same point. The solenoids might be shorted / burnt from stuck operation.

Again... hope it helps.

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As budwich is pointing out, there are a lot of different components that get power through the ECC fuse and relay (transmission solenoids, engine computer, CANP solenoid, EGR solenoid, MAF, and so on. Essentially the entire engine management system). If you don't have a wiring diagram that shows most of these components, I would suggest finding a decent diagram. The wiring diagrams in the vehicle repair guides at www.autozone.com are a decent start.

So i just figured something out.

IF i dont have the key turned to the ON position, the side of the fuse that seems to be grounding out, is no longer grounded out. I'm verifying this by ohming with the negative battery terminal. Maybe not the best, but the negative cable off the battery does go to ground.

Anyways.. so the fuse is only grounding out when the key is on, that means that it's not a physical wire failure.. right? cause if it was, it would still ground out?

Unless... hmm.. if the wire ground point is on the other side of the EEC relay.. then i wouldn't see it until i turned the key cause when i turned the key, that's when the circuit would be connected. hmmm.. i think my one option is to find out where the EEC power relay unit is, and replace it and cross my fingers.

Anyone know where the EEC power relay unit is on this engine? I cant find any mention of it in the Chiltons manual i have. I have a 91 explorer V6 i think 4.0L 4x4.. looks like this http://www.bigmountain.shoppingcartsplus.com/i/tn_engine.jpg

its in the fuse box nxt to all the fuses, the big black thing your maual will tell you which one it is.

I wouldn't blindly change the ECC relay. Just unplug it and measure the contacts as suggested earlier. In addition, a 30 amp fuse (on the "feed" leg of the relay and assuming it is the one you see blowing) is going to see something like .4 of an ohm which will look very much like a short if your meter is not well calibrated. The ECC relay only operates with the key turn which is normal. Potentially, you need to unplug as many things as mentioned ealier (and more... follow the feed path from the ecc relay) until you are able to have the ecc operate and not blow the 30 amp fuse.... and / or measure each individual "take off" unit and see if there are shorts / low resistance readings on them. good luck... it is "findable" because it appears to be a hard short / low resistance.

lonestar said:
I believe on a first gen the relays are actually below the fuses in the Power Distributin Panel under the hood. You will need to the fuse panel to get to the relays.
The relays are underneath the black Power Distribution Panel fuse box on the passenger fenderwall under the hood. I never removed it, but the top fuse panel should be removed to reveal the relays.


Clean your battery terminals. When you turn your key on, what happens to your voltage gauge in the dash?

Yeah, the relays for a '91 are under that fuse panel under the hood. There should be slots in the metal mounting plate and if you lift up on the fuse panel it should slide out upward revealing the relay box beneath. The relay box slides up and out the same way but there's a metal locking tab on the mounting plate you need to depress with a screwdriver to get the relay box to slide out, once it's out flip it over and you'll see 3 relays. I'm not sure which one's which, but if your X is anything like mine they'll be color-coded, I believe one grey, one brown, and one green.

------------------- ^ Up
| fuse panel |
|| || <-mounting rails
| relay box |

should be similar to that, hope this helps a bit anyway...

I went down to ford, got an EEC relay for 25 bucks, replaced it, and the problem is not gone. So I went further. Voltmeter in hand and a wiring diagram beside me, i went to work. I'm an electrical engineer so i know what i'm doing with a Voltmeter/Ohm-meter.

So here's what i've found. The wire highlighted in yellow in this diagram is all grounded. At all points, well, all the points i could get to. I ripped the kick panel from the passenger side and pulled the plug and tested that, all grounded at 37 and 57. I removed the Mass Airflow Sensor plug, tested the red lead, grounded. Checked at the spark plug connections, grounded. Couldn't find the Canister purge solenoid (have no idea what the heck that is or what it looks like).

Do you guys think i could possibly rewire this wire? I know it's probably just asking for trouble, what do you think? I think that might be my only hope of remedying this ground out situation cause i dont think i'll EVER find it.


The only other thing i can see that i should check is maybe the following:

1. Find the Camshaft position sensor (as that has a ground and could be faulting and forcing that wire to ground) and test it.
2. Cut the red wire to the mass airflow sensor and see if it's still grounded. Then re-attach if it is, this means it's not the mass airflow sensor.
3. 21, 33, 24, 31, 53 and 52 should not be grounded with the car OFF as circuits should be broken at solenoids if no power is applied to solenoid.
4. Find a wiring diagram for "To A/C System" and check connections there for grounding.

am i correct in these assumptions?

1) Make certain you have a CMP. I don't know where you got the diagram you're showing (looks exactly like the diagrams from www.autozone.com or Chiltons), but I have seen inaccuracies in those wiring diagrams. For example, your diagram shows an EVR solenoid, but, to my knowledge, '91's didn't come with an EGR system, so there shouldn't be an EVR solenoid. Some years had CMP, some didn't (my '92 doesn't have a CMP). If you have a CMP, it will be at the rear of the motor where you would expect to find a distributor cap (if you had a distributor cap).

While discussing locations. CANP solenoid on my '92 is inline with the vacuum line running from the charcoal cannister to the throttle body. In other cases, the CANP is attached to the throttle, but still on the same vacuum line.

Beyond that, 2,3,4 look good. You're going to just keep eliminating possibilities until you find the ground.

Could you rewire the red wire? I'm sure it's possible. I don't think it would be easy. That red wire feeds a lot of components. And rewiring is only going to fix the problem if the fault is in the wire itself. If the problem is in one of the components that is fed by the wire, rethreading the wire wouldn't make a difference.

Good luck.

Not sure how easy it is, but you might want to try pulling any obvious grounds from the powertrain control assembly (20,40,60??) and see if perhaps the grounds "disappear" from the affected terminals you noted / checked.