Dparr2ndgen

I have been having an electrical issue with my runner for the past few weeks. At low rpm (idle up to about 1200 rpm, after that it goes away) I get the parking brake and battery indicators on the dash (which from previous searches on here suggests a bad alternator.) I recently took the alternator to autozone where it tested fine. I can therefore only assume that perhaps the wiring between the alternator and battery is grounding out somewhere. Here is my tentative plan I attack for fixing, please let me know if I am missing something.

I looked high and low throughout the forum and couldn't find much directly referencing the lights going off and coming on with engine rpm.

1. I am going to start with the fusible link from battery to fuse block under hood. This is hacked up by the p/o and I snagged an OEM one at a salvage yard. Can that potentially be my issue?

2. I plan on testing the alternator and charging system per FSM. It suggests using a voltage meter and ammeter at the same time to read voltage and current. Can I do this with one meter by first testing voltage and then relocating the leads to test amperage or is that not an option?

3. Since the wire from alternator to the battery is not an available part at a local store, is it acceptable to splice/ run a new piece of 4awg or equivalent to what is under the good stock?

3. Also, the ground from the battery to the fender is definitely an aftermarket job. For clarification purposes, this ground should go from the negative terminal to the fender yes? I have seen vehicles with either positive or negative grounded and wanted to make sure the negative was the ground.

It's a 91 runner 3vze powered 4x4 mated to an r150.

Thanks

wyoming9

iTrader: (1)

First Check to make sure your belt is tight.

Does it squeal at all?? Just might be time for new belts

Did you have the battery tested as well??

Does the charge light stay on as long as the engine only idles like if it idled for 10 minutes would it go off??

First you should measure the voltage at the battery and go from there.

First off the warning lights just point to the voltage being out of range they also trip if the voltage is to high.

Yes it could be the alternator but one never knows without testing the whole charging system

Negative ground system you should have the ground to the inner fender and a ground wire to the steel engine block.

Yes you can splice (I just replace the whole wire) in a new 4 gauge wire just make sure your crimps are good. The wire from the alternator B terminal should go to the fuse block in the engine compartment.

If I remember correct the factory uses 8 gauge using 4Gauge the lugs might be to big to fit where needed

Anything from poor grounds to poor connections can cause this issue

I have never used an Ammeter to trouble shoot most all engine electrical problems. Most of the time I never needed it or was to lazy to drive to work and get it Then only to perhaps check the starter draw

Dparr2ndgen

Thanks for such prompt input! I think I will start by swapping out the fusible link (p/o spliced in narrow gauge speaker wire then wire nutted it all together) I have a factory link I will swap in first. The belt is a brand new Dayco belt, (although this issue was happening with the older belt.)

I feel like I had been getting adequate tension, however one thing did happen. I could get the belt tight enough that, at first the lights would go away, but minutes later would come back on. Do I jut need a big pry bar then and tons of tension? Also, when the light comes on it does stay on until I go back and tighten it again. Maybe the belt is stretching just enough that as it heats up it's not staying tight enough. Perhaps I should try the fusible link and more tension on the belt first. Battery is good only about 30 days old. I am a little Leary of over-torquing the 10mm bolt that holds the alternator at tension, but maybe that's what it takes in this scenario

Gromjs

Another way to test a alternator is with the motor running touch a wrench to the back of the alt housing, if the alt is in working order you should feel a magnetic field pull the wrench, also I would try a different ground wire, they do break down over time.

Dparr2ndgen

Thanks! I will try the wrench/ magnetic field method.

When you say run a new ground. Do you mean a new ground from the battery to the fender?

Gromjs

There should be a ground to the block from the battery, in most cases they fail do to heat and oil and whatnot degrading them. Just clean the surface that it contacts and try a new cable. I'm no master mechanic just putting in my .02¢ worth.

Dparr2ndgen

Sounds good, I appreciate the tip. I will likely read up on the "big 3" change-out that is well discussed on the forums and give that a try as well. In your opinion do you think since the dash indicators are not coming up at low rpms that it is more likely a connection/ grounding issue as opposed to an alternator problem?

Gromjs

Yeah them not coming on leads me to think that ground cable may be busted up inside from heat, therefore it may be the equivalent to a cable half it's size and simply isn't enough when the alt feeds more amperage to the system.

2nd gen trail truck (work in progress), 61 vw bug (daily driver), 84 subaru wagon (waiting to be beat on again), 78 subaru brat (project), 81 f-150 (tow rig for now) , vw sand rail(work in progress)

Dparr2ndgen

Well I went ahead and cleaned up all grounds and changed out the fusible link and main fuse. Vehicle seems to let over quicker now but no luck on the charging scenario. I took my alternator to the local auto parts store and they said the alternator is only putting out 11.5 volts at idle. At that voltage it certainly won't charge the battery, so it seems like that is the issue. I also noticed the copper lug that attached to the alternator is very corroded. Going to swap that out and install a reman alternator and see how things go! Thanks for the help

wyoming9

iTrader: (1)

Both bolts need to be tight that hold the alternator.

Other wise it will come loose.

Let us know how you make out.

Dparr2ndgen

Well, good news so far! Reman alternator installed with new lugs crimped on either end of the wire. No dash lights and battery reading right around 14 volts! Alternator does seem to whine a bit, could that be a symptom of it being newer? Or should I play with belt tension and see if it goes away?

Thanks for all of the tips once again, I still plan on changing all grounds, but it's nice I can do one here and one there and still have a working vehicle