Charging circuit troubleshooting, possible alternator issue (1 Viewer)

[MJC70]

I have an 88 FJ62, recently the battery light, brake light and AT oil light all come on and stay on after starting the car. Using the search button points me to charging circuit.

I've checked and verified continuity in the fuses and fusible links as well as the wire that runs from the fusible link to the alternator. Charged the battery to full charge last night and took some load readings, about 12.7 volts while idling then closer to 12 volts while under 2k rpm load and lights on. The battery is only a couple months old so I don't really suspect it.

Lights have always sucked on this thing but they do seem dimmer as of late. I've also got a flat spot on the starter I have to give the Fonzi treatment to about every 20th start though maybe not related. The readings don't seem "that" low to me but it looks like spec should be 13.8-14.4?

Is there anything else I should check before I pull the alternator to get it checked out somewhere?

I'm inclined to buy a reman and then send mine away for rebuild and have a spare but maybe there's a direct replacement I should go with? Planning on adding a wench and lights in the future, is this reliable on the OEM alt or should I look into more capacity?

 

[Seth S]

With the engine off the battery voltage should read 12.6 volts. With the engine running you should be seeing 13 - 14.4 volts. It sounds to me like your alternator isn't charging. Are you battery terminals clean and tight? Are all your battery cables in good condition? Is your fusible link still in good condition?

Start the truck, put one terminal on the output post of the the alternator and put the other on battery ground and read the voltage. If while running the voltage isn't 13v or higher try wacking the alternator case with a hammer a couple of times and see if the charging voltage increases.

 

[MJC70]

Start the truck, put one terminal on the output post of the the alternator and put the other on battery ground and read the voltage. If while running the voltage isn't 13v or higher try wacking the alternator case with a hammer a couple of times and see if the charging voltage increases.

Thanks Seth, tried give the alternator a few good hits and reading 12v at idle and 11v with lights running from battery post to alternator post, will pull the alternator to get tested but pretty sure thats my culprit. Recently replaced all my battery cables and was running fine for about 3k miles, just replaced all my fusible links but getting continuity from the ground terminal to the alternator and across the fusible links.

 

[Hammer45]

I have an 88 FJ62, recently the battery light, brake light and AT oil light all come on and stay on after starting the car. Using the search button points me to charging circuit.

I've checked and verified continuity in the fuses and fusible links as well as the wire that runs from the fusible link to the alternator. Charged the battery to full charge last night and took some load readings, about 12.7 volts while idling then closer to 12 volts while under 2k rpm load and lights on. The battery is only a couple months old so I don't really suspect it.

Lights have always sucked on this thing but they do seem dimmer as of late. I've also got a flat spot on the starter I have to give the Fonzi treatment to about every 20th start though maybe not related. The readings don't seem "that" low to me but it looks like spec should be 13.8-14.4?

Is there anything else I should check before I pull the alternator to get it checked out somewhere?

I'm inclined to buy a reman and then send mine away for rebuild and have a spare but maybe there's a direct replacement I should go with? Planning on adding a wench and lights in the future, is this reliable on the OEM alt or should I look into more capacity?

Howdy from Texas.

“Planning on adding a wench and lights in the future, is this reliable on the OEM alt or should I look into more capacity?”

did you decide on the answer to this question? I’ve got my ‘89 fj62 torn apart and I’ve got the same question. No problem with the current (no pun intended) alternator though it hasn’t seen action for a few months. Thanks, d

 

[MJC70]

did you decide on the answer to this question? I’ve got my ‘89 fj62 torn apart and I’ve got the same question. No problem with the current (no pun intended) alternator though it hasn’t seen action for a few months. Thanks, d

Didn't really get a consensus looking at forums, I ended up putting in a mean green alternator (more capacity) and I'm also having the OE alternator rebuilt for a trail spare. When I get it back I'm going to try to see if I can make it fit where the smog pump is and try to run a separate charging circuit/deep cycle battery. No clue if it will fit there yet, I've read you should run the winch off the battery directly connected to the alternator but would like to keep it separate from the original equipment just for peace of mind. haven't seen anyone do it on an fj62 yet so maybe I'm spinning my wheels...sorry if that didn't really answer your question