89' Bronco 5.0 EFI

My Bronc has no power at all! Heres the senerio... Parked it this past Thursday night 2/16. Tried to start it Friday morning 2/17. Starter just acted like the battery was bad. Took the battery to 2 different auto stores to have it tested and it passed. Initially the starter just tried to turn, after I put the battery back in the solenoid just clicked, no starter. I already replaced the starter and starter solenoid on Monday 2/13 with a new, not reman starter. at this point Im just throwing parts at it. This past weekend I replaced the ignition tumbler, the ignition switch on the column and today I replaced the EEC relay. When I check voltage to the stater solenoid I get voltage to both sides??? I also get voltage from the red ignition wire to the top of the solenoid. Otherwise have zero power to the rest of the truck. No radio, no dome lights, no headlights, power locks, power windows or back glass. What gives?

 

WITH THE TRUCK IN PARK OR NEUTRAL what happens when you take a small wire and jump point #3 to point #5 in the diagram above on your solenoid on the fender?

 

Ill give it a shot when I get off work tomorrow afternoon. Is point #5 the IGN stud on the solenoid? If so I tried that already and nothing happens in PARK but havent tried it in Neutral.

 

Point 5 is the "S" post; it's the trigger signal from the key.

If you're getting voltage at all three points on the solenoid with the key in START (or tried the test Franklin2 described) and the starter STILL does not turn, then the starter must be binding somehow and cannot turn. Are your battery cables getting hot?

The dead electrical system sounds like a blown fusible link. However, if that were the case, you would never get voltage at the 'S' post of the solenoid with the key in START, and the solenoid would never make. Has this truck's wiring been modified or cut up at all?

 

No the wiring on this truck is in all original condition with absolutely no PO add on's. I tried the test with the above diagram a moment ago with no results. When you turn the key nothing happens at all as well as no power to anything in the truck. But there is power to both sides of the starter solenoid and the "S" post.

 

Check your GROUNDS.

 

"No power to anything in the truck, but there is power to all points on the solenoid". That doesn't make a lot of sense to me right now. Do you have headlights? If you do not have headlights, and absolutely nothing comes on, no blower motor, no domelight, no gauges, no radio, nothing, then I would say you main fusible link is blown, and it's hooked under the large wire at point #3.

I am digesting your first comment I quoted above, and I am wondering where are you putting your black meter lead when you are testing for voltage? If you are putting it directly on the battery, take it off the battery and put it on a good scratched off piece of metal on the engine. If you get voltage readings with the black lead on the battery, but get nothing with the black lead on the engine metal, then I agree with one of the other posters, you have a large cable ground problem from the block to the battery negative post(point 2 and 4.

 

Yes... NO POWER to anything. No headlights, no dome, no radio, nothing. And yes Ive been testing from the battery ground. Ill scratch the block tomorrow when I get off and try it all again.

 

Dave posted a diagram where the cable coming off the pos. post of the battery goes to point 3 of the solenoid. At that point you should have another eye connection coming off of the alt. output and another that feeds the power for the headlamps and also the ign. ect.

 

Well, any progress?

 

Well I thought so. I separated the new (not reman) starter from the system and did voltage and continuity test on the system and everything functioned just fine. Put the starter back in and the truck fired right up. Took it to Autozone to have the battery checked for the 3rd time and it passed but with about 85% charge. It once again fired up there, I drove it home and left it be. Just went out and started it a moment ago and it fired up then shut it off. Tried to start it again and its doing the same thing again. I have good engine ground and complete continuity through the starter cable. No blown fuse links anywhere in the truck. and the battery checks out. It has to be a bad starter, has to be...

 

Agree 100%! You're experiencing what's called "heat soak" meaning once the starter is hot its internal resistance is high enough there's not enough current in the battery to spin it over. IF the testing shop tested it immediately after you typically have this problem they'd see this quite easily.

Hope you get this sorted out---been there, done that on another vehicle and its aggravating AND unreliable as can be!

 

You really can't check continuity on the heavy wires. The only way you can really test the very large starting wires and the large ground wire, is to put a voltmeter downstream, and get someone to try and start it while you take voltage readings. Here's the reason why;

Let's say you check the continuity from the battery end of the ground cable to a clean metal place on the engine. Let's say you get .25 ohm, which you would think is good. It's not. Depending on the engine, the starter, and weather conditions, the starter can pull around 150 amps when the engine is cranking. Voltage=current x resistance. The voltage lost in the .25 ohm cable will be 150amps x .25 ohm= 37.5 volts lost. You only have 12 volts to start with, so you will get nothing to the starter if the cable has just .25ohms resistance.

Keep going with your troubleshooting, but I am just explaining your "checking continuity" is not really going to help you solve your problem.

 

Im taking the starter back up under warranty and telling them it is an intermittent issue and let them worry about it. While Im there Ill pick up some new battery cables and let them retest the battery

 

Superb post Franklin----explains this condition perfectly!!