94 touring wagon ecu fuse

[91legacyawdturbo]

I'm trying to help another turbo legacy enthusiast's car up and running. The car itself is a 1994 touring wagon with the ignition on its blowing the 15 amp fuse at fuse 16. I've looked at the fsm and also Deloomed a spare turbo auto bulk head harness also took apart a spare fuse box the goes under the dash. The fuse box panel splits the power between the forward harness to the intake manifold. That harness powers the alternator, injectors? The ignition diodes. Second harness which is the bulkhead powers the ecu at f58 pin 12, igniter, tcu and the fuel pump relay both harness connected at the fuse box or disconnected show infinite olms. I swapped in a known good ecu and it still popping fuses. About to start pulling each component off and retest the continuity again of all the components that the harness's connect to. Any ideas or past experiences? What can be a shared circuit for both harness that could cause this? A crossed or chaffeured ground to a power on the harness itself????

[Legacy777]

Take a look at the first 4 pages of these diagrams.

http://main.experiencetherave.com/subar ... agrams.zip

It shows the power supply routing and what is on that circuit. Fuse 16 supplies circuit FB-26 which as the ECU, TCU, & fuel pump relay as well as tying into the alternator's "turn on" switch.

My hunch is something in the alternator is fried and grounding out that circuit causing the fuse to pop. Check out pages 6-7 of 82 in that pdf for info/testing on the alternator circuit. An easy test would be to simply unplug the round alternator plug and see if that keeps the fuse from blowing. If it does, I'd double check the alternator wiring to make you don't have a short there; and if you don't then it's something in the alternator.....and time for another alternator.

[91legacyawdturbo]

Thanks Josh, I disconnected every thing an one at a time I reconnected the components an it did blow the fuse but the alternator does sound like crap while idling.

[Legacy777]

Did you unplug just the alternator to see if the fuse blew with the key in the ON position and car not running?