1987 bronco 2 won't start

[Duane867]

You can mess the eccm up causing all kinds of weird shit to happen with out completely frying the whole thing to the point of completely dead. Chips can come unseated, solder can crack, pcb boards can crack, moisture can build in them. All sorts of crap.

May or may not be the problem but it happens.

For the record though,the eccm does not control the radio, nor does it control all power to the truck under the hood. It manages the fuel, air and timing systems.
It could still crank and crank and crank in most instances but not start as long as the ignition switch, solenoid, battery, and starter were still good. Could you loose all power inother instances, yup. But not always, and not definitely.

 

[Spott]

Hmmm. You gotta try a few things to isolate the problem.

First, unhook the battery completely. Clean the top of the battery thoroughly. Measure the voltage with a multitester. Ideally, it should be 12.6 volts. It should read over 11.8V when measured. If it's below that, charge it up with a good battery charger, allow it to cool, then measure again. If it's above 11.8, it might be good, but wait 12 hours or so and measure again, to double check. If it hasn't dropped, the battery is good. Hook it back up.

Second, check the charging voltage and the regulator. With the engine and all accessories off (and the battery connected) the voltage should be over 11.8, just like the previous test. If it's low, something is drawing your battery down, see the next test. (jump)Start the engine. At idle, the voltage across the battery terminals should be 12.6V or higher, but not over 14V. At higher RPM's, the voltage should be a approx 13.8V. If it's much higher than 14V at high RPM's, your voltage regulator is bad. Replace it. If the voltages are lower than this, either your alternator is bad, or you've got a big load somewhere drawing more than the alternator can supply (examples include massive stereo systems or lighting systems, or a power leak to ground.) Take your alternator to an electric motor/alternator shop and get it tested.

Finally, make sure nothing's discharging the battery while it sits. The only things that should be getting power from the battery, with the truck off, is the clock and the radio memory. They draw extremely little current. So, with the truck off (doors closed, key off, etc, like you're going to leave the truck in the garage for the night) unhook the negative cable from the battery, and hook the black(negative) lead of the multitester to the negative battery cable. Set the multitester to the highest Amps or Current (A or mA) you have, then attach the red(positive) lead to the negative battery terminal. See what the reading is. If it's too small to tell, change to a smaller range. The current draw should be less (much less) than 100 mA. If it's measured as more than that (or you blow the fuse in your multitester) then you've got something drawing power from your battery, and discharging it while it sits.

Let me know what you find out, and I'll help you proceed from there.
Spott

 

[n_grimm]

Along with the excellent advice above, if the starter won't crank it over on it's own without being jump started, pick up a $20 battery load tester at Harbor Freight or somewhere. Then test the battery after charging to see if holds up under a load, verify the resting voltage, charging voltage and cranking voltage. Especially helpful if you don't have a voltmeter handy. It sounds like you may have more than one problem but you have to start somewhere.

 

[eclipse2001gt]

well found out the battery was part of the problem but still have power going through the tail lights with out having the light switch pulled out to have them on.

Put water in the battery and now it is holding a charge and drove it around town with out any problems but still having the power going to the tail lights for some reason.

 

[Duane867]

Have you checked the loom running back to the tail lights ? Checked grounds, switches, and such ?
I mean the full length under the frame, not just a foot or so near the lights.