86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

1990 Toyota 4Runner 4d 4wd battery drain

Old 02-06-2019, 12:57 PM
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1990 Toyota 4Runner 4d 4wd battery drain

I have just finished rebuilding the engine on my 4runner. We put a brand new Optima battery in it and now we're having problems keeping the battery charged. Any ideas?
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Old 02-06-2019, 01:40 PM
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Welcome to YotaTech.

Do you have a multimeter? If not, Stop. Do not pass Go. Get one:

Put the multimeter leads on the battery posts. With engine off, you should get something close to 12.6v (temperature dependent). At idle, you should get 13.9-15.1v (also temperature dependent).

If that checks out, you might have some parasitic battery drain. Engine off. Set your multimeter to the 10amp range. Use something like a twist-tie to hold the red lead to the + battery post, and the black lead to the cable that connects to the SAME post. (If you hook it up across the battery, it will instantly blow the fuse in the meter -- if there is one.) Carefully disconnect the cable clamp to disconnect it, leaving the multimeter as the connection from battery post to cable. You should get much, much less than 1 amp; probably closer to 0.020 amps (just enough to keep the clock running).

Last edited by scope103; 02-06-2019 at 01:42 PM.
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