Forerunner will not start, battery is fine

[Finnguala]

I have a 1990 Forerunner, automatic, V6, over 300,000 km on it.
I purchased it about 6 months ago.
In the last 4 months I have not been able to start it without a boost. We checked the battery, it is fine.
I am very careful to make sure lights, radio, fan are all off before I turn it off. The odd thing is a few times when I have been out doing errands it would start ok the first few times, the next time would take a few tries and then it would start, the time after that it would not start at all. My husband thinks there may be a parasitic load on it somewhere, and he is going to run some tests.

My question is, is there a typical load on a 1990 Forerunner that would account for this? Another typical reason this would happen in a Forerunner? Any diagnostic tests recommended?
Thanks so much!

 

[the_dingman]

Forerunner:

4Runner:

:bluejump:

Take the negative battery terminal off, and put a multi-meter between the netagive terminal and the negative lead and measure amperage. This will tell you how much load there is. Then, pull fuses one at a time and see what makes the amperage drop. This will at least point you in the right direction.

If you don't have a meter, I reccomend the 22-223 from RadioShack for $26.99.

 

[Awz]

Also check the battery terminals (if you haven't already) The nut on my negative cable likes to back itself off and nothing I can do will stop it, it causes that exact problem, starts fine sometimes other times needs a jump and acts like the battery is near dead. Also check where the negative battery cable grounds to the body, it may be loose or corroded. If those fail then I would think you have a parasitic load somewhere.

 

[fourwd1]

The load will depend in part on what accessories are installed, clock, stereo, alarm, etc.
Somewhere in the range of 50-75 mA would probably be average.

Definetly make sure both ends of both battery cables are clean and tight.

 

[bigbsvo]

It sounds to me like a bad connection between the cable terminals and the battery post. Pull the terminals, use a battery brush to clean the inside of the terminals, clean the post, then re-attach the terminals and tighten them. Sometimes the terminals need to be replaced if they have heavy corrosion from an acid leak at the top of the battery.

I will bet that is the problem since you stated the battery is fine and you did not state that you have to recharge the battery since, like you said, it is fine. Right?

No automobile technicians in Canada, ay?

 

[Finnguala]

My husband is actually a heavy duty mechanic, but with very little time so I thought I would try to help him out by getting some ideas of typical problems these vehicles have.

He went over all of the wiring last night with the multimeter, and the problems were the dome light, but also the security system that was put in. We were not given any info on it when we bought it. When he disconnected that, there was a significant change in the load on the battery. He said the wiring for the security system was really screwy, and wonders if there was some sort of immobilizer-gone-wrong as well that was causing the unpredictable nature of whether it would start or not.

 

[Finnguala]

Forerunner and 4runner. I actually own both of these. My bad, I will remember for next time

 

[the_dingman]

Forerunner and 4runner. I actually own both of these. My bad, I will remember for next time

I hope that didn't come off rude, meant in fun! :biggrin2:

Glad to hear that you might have found the problem!