01 4.0 electrical issues

[chris013087]

I have an 01 4.0 ranger that was running fine until the other day. It started with the ABS light flashing. It did not stay on but only flicked on and off for a few times. The next day while driving the tachometer started going up and down, while driving down the highway to work at a constant rpm. Also the radio just shut off on its own. I pushed the power button and it came right back on, but the rpms never did until i shut the truck off. I was in work for a few hours came back out and tried to start but the battery was not strong enough to turn the truck over. The radio still could turn on though and while I was waiting for a jump i turned the key on and off while doing this the radio turned on even when the key was out of the ignition. I have pulled out every fuse and relay, unhooked the radio and the battery is still getting juice pulled from it. I have no idea what the problem is any advice would be very helpful.

 

[wvcat]

Not much help but it sounds like a short in an electrical connector or fuse box. Have you had anything unplugged recently?

 

[desertrat]

This may not be your problem but it is an easy test and you should do it right away: Check your alternator - soon. I recently blew up my ABS Module and the radio because of a rebuilt but bad alternator. And it had a slow drain on the battery with the engine off; would kill it in about 3 hours. It was pumping about 40 amps at almost 18 volts into the system - all the time. And it was putting some AC into the system. I do not know what was wrong with the thing - suspect bad diodes, etc - but it cost me some bucks. The things you describe would go nuts if they are getting any AC power. Get a good Amp Clamp and hang it onto your positive battery cable. A few minutes after the engine starts the amps should drop to 10 or less. Then stick a volt meter across the battery terminals with the engine running; It should read around 14 volts. I did not suspect the alternator at first because it was almost new. That cost me.