AM2 30 amp fuse keeps blowing

I have a 97 tacoma with a 2.4 liter. External distributor. The am2 30 amp fuse blew. I replaced it and drove about 50 feet and it blew again. Any help would be greatly appreciated.

 

You going to need to trace (follow) the wires to see where they/it is shorting out.

 

I've looked in the book for the wiring diagram. It is not specific on what that fuse powers. I think it runs to the distributer. I've googled it and I am at a loss. If anyone out there has the wiring diagram that this fuse powers it will narrow my search.

 

I'm having the same exact problem right now, did you ever figure it out?

 

I am not at home so I dont have access to my wiring manual... having said that, I think the issue is wires shorting in the distributor and/or the capacitor.

 

My wiring manual is for 1996 Model year... I hope it is the same.

The wiring shows the following. White wire from battery to AM1, AM2 and ALT fuses.
from AM2 fuse to White / Red wire to ignition switch
from Ignition Switch Black / Red wire to a connector just beyond(inside) the grommet that seals the harness.
unplug this harness and turn the key to "ON" if the fuse blows there is a short after the switch.
From that harness the Black /Red wire crosses over to the Passenger side kick panel to yet another connector then the Black /Red wire gets a splice that goes 3 ways.
Igniter, Distributor and Ignition Noise supressor all Black / Red wires.

hope this helps.

 

I would simply start by unplugging the distributor and ignitor, then with the key on see which one possibly blows the fuse. I doubt the noise filter is the issue, but its possible as well.

 

What I see from all years diagrams in 2.4 AM2 powers only 3 things:
- Injectors
- Ignition coil
- Noise filter

If your engine is running without problem I doubt it would be injectors. Not for 30A. You can always verify resistance of each injector: should be 13.8ohm.

Ignition coil ma have possible shorts between wires - might still give a spark, but taking higher current than it should. Hardly but possible.

Noise filter (electrolytic capacitor) might actually do that - under the power might first heat up and then get short. That is delay effect you are describing.

I would check in that sequence:
- Noise filer
- Loose wires with cracked or rubbed off insulation
- Ignition coil primary resistance (by the book should be between 0.33 - 0.55 ohm cold, 0.45 - 0.65 ohm hot).

You can disconnect noise filter (I'm not sure how it is connected in your engine) and see if the short goes away.

For loose wires it might be tricky to find. If it is not immediate short but after "drove about 50 feet" it will be difficult to replicate or locate. You would have to remove AM2 fuse, disconnect all injectors and ignition coil, and measure replace the AM2 fuse with buzzer. Then going through all harnesses involved shake them, move them to see if buzzer goes off.

Ignition coil is also difficult to measure accurately with simple "home use" multimeter. The only way to do it without quality ohm-meter would be using Volt-Amp method. Power the the coil through 3W bulb and measure the current and voltage drop on the coil. Doable with two Harbor Freight 3-dollars multimeters. The accuracy of this is good enough to find out if low primary coil has a short or not.

 

1995 tacoma 2.7l, The am2 was blowing and disconnected the distributor and short went away. Found the capicitor in the bottom of Dist. was shorted. dissconected the capicitor from the Pos. terminal on the coil and short gone and truck runs. truck has 300k miles on it. This forum helped me find the problem.

 

Thanks this helped saved me a lot of money. The Distributor Condenser part number is 1913316240 from Toyota.