hey everyone, new to the site. just got an 88 4runner that has 137000 miles and was running great. It started running rough below 2500rpms and the charging and brake light (which is disconnected) came on. Truck still starts and idles fine but only charging at 8-10 volts. any ideas.

 

Well, usually if your battery stops charging it means your alt is bad.
You can remove it and have it tested.

 

forgot to mention oil pressure drop at idle and the speedo flipping from 0 to 100 but eventually working

 

Electrical signals won't work right if the voltage is wrong.

 

the altenator was my first thought, but i drove 30+ miles with the lights on, cold temps in the teens and it started right up next morning. I'll have the alt tested just wondering if I should look elsewhere, didnt seem like my past experience with altenator issues. On a side note, went to check the oil(new to me truck 30 hours) cant find the oil dipstick! prior owner had the oil changed and wonder if its missing.

 

I found the issue. Pulled the alt and it tested fine. When I was reinstalling I was in a hurry to beat freezing rain and darkness, and forgot to disconnect the neg battery terminal(noob). Well it grounded out and blew the 80a engine fuse. When i disconnected the fuse block, the lead to the battery fell apart. replaced the wire and everything is well again. The alt belt on the otherhand... any recommendations on a good electric fan.

 

Glad to hear you found the problem and welcome to Yotatech!!!!!
The common electric fan swap on these is to use one from a Mercury Villager minivan. Search the forums you'll find tons of info!

 

thanks

 

Good to hear you got it fixed. Don't forget to replace the main fuse box ground wire. Use a heavy battery cable. If you look around you will find my post about it.. makes a big enough differance to warrent $10 and 30 min of your time especially if you have lights and stereo upgrades.