97 GTS Keeps Blowing PSM/ASD Fuse

[Zrxpilot]

Really hoping someone can help me with this. Was driving fairly aggresively at highway speeds, dropped a gear coming off the ramp and it just quit. Found the big 20 amp PSM/ASD fuse blown. Put in a new one and it started right up. Was driving it home and all was fine. ****canned it coming onto the freeway and it happend again. Seems if you take it easy its fine but as soon as you give it some it blows this fuse. Ive have the car on blocks this evening and looked everywhere top and bottom for a severed wire. Figured something was touching a header or something. Took the crank sensor heat shield off and inspected that. Looks fine. Even went so far as to have it running on blocks and wiggled every wire I could find in hopes of replicating the issue in the garage. Im stumped. It appears by reviewing the manual its somewhere in the ignition system. Thinking maybe its got something to do with this automatic shutdown system. Perhaps I should change the relay?

Any thoughts would be greatly appreciated.

 

[Tom Sessions]

Look at your o2 sensor wiring and make sure its not touching a header. Have seen this before drivers side below and a little back from the power steering pump. is a good area to check first.and if the o2 wires are still straped to the engine mountslook at them as well.

 

[Zrxpilot]

My buddy has this hand held computer that reads codes by plugging in somewhere under the dash below the steering wheel. Hes had it hooked up to my car before. Would it do any good to run my car till the fuse blows, and plug in this computer immediately afterwards to pinpoint the issue?

 

[Jack B]

The 20A fuse in cavity #15 splits into two circuits:

1. The first circuit goes directly to the the PCM. That is a red/white wire. Since it is so short it should not be a problem. Just verify the integrity.

2. The second circuit goes into the ASD relay, it splits and two wires leave that ASD, both are in series with the 20A fuse, therefore, either of these two circuits could affect the 20A fuse.

a. The first circuit goes to the two rear O2 sensores, but, as the circuit leaves the ASD relay it goes thru the 15A fuse in cavity #1, therefore, if the O2 sensors conductors have an issue they should also open the fuse in cavity #1. Check that it is still a 15A fuse. This probably rules out the O2 Sensor wiring.

b. The second circuit (dark green/orange) leaves the ASD and goes to the PCM, again check the integrity of this conductor. This is so short the odds of an issue are remote.

With all that out of the way the relay should be replaced, it might be the issue and it is cheap. Tom's suggestion of the O2 sensor conductors makes sense, except, it should have the 15A fuse in cavity #1 in series with the problem and that fuse would open along with the 20A fuse.

To complicate it even more, I believe some early 97's did not have the 15A fuse included in the O2 circuit, that cavity was a spare, with that in mind, Tom's suggestion makes the most sense.