Radio, Power Steering, Engine cut out while driving

A new issue has cropped up with my 2001 H6 Subaru Outback (which I believe is technically a Legacy). We’ve put so much work into this thing to keep it running and this might be the last nail in the coffin. However, I’m hoping people can help figure out what’s going on…

My wife reported to me yesterday that the vehicle was turning itself off while driving. I was not in the car to verify any of this, so this part is anecdotal. After 45 minutes of driving, she said the engine was “hiccuping” and the gages were dropping to zero and then bringing themselves right back up to the current RPM and speed. She said the ABS light came on. The first time the vehicle did this, she reports that it did it many times in rapid succession. She described it as “the gages were going crazy”. After turning around to come back home this happened once more, though not in rapid succession. It was a single occurrence of turning off and back on again. She indicated that the vehicle did not require a restart with the key. I suspect that this was because she was driving at highway speed at the time.

She brought it right to the mechanic and - as is the case with all intermittent issues - they were not able to repeat the failure in any way. So, being an engineer, I decided I wanted to experience it for myself and do a few tests.

Today I drove 45 minutes to work, 10 minutes of small town driving, 25 minutes of highway driving, 10 minutes of small town driving. Lucky for me (!), in the first five minutes of driving, the radio cut out, power steering died, and I heard fuses or relays clicking as I was gently braking and gently taking a right turn. I continued the right turn off into a parking spot on the side of the road and stopped the car. I turned the key to the off position, put it into park and restarted the vehicle right away. No problems. All was fine.

The vehicle did not do this again for the entire trip. However, I did perform some tests to see if I could repeat a similar failure with the ignition alone.

  1. Turning the ignition off and quickly back on again by hand while rolling at highway speed (~55 mph) will cause the vehicle to kick back into a normal running mode.

  2. Turning the ignition off and quickly back on again by hand while rolling at lower speed (~30 mph) will require a restart by turning the key all the way to the “start” position and not just the “on” position.

  3. Turning the ignition off with the key (as in 1 and 2) DOES NOT cut out the radio. Note that when the intermittent defect occurs, the radio will cut out and then come back along with the engine and instrument panel.

  4. Wiggling and stressing the keys to put strain on the ignition switch doesn’t seem to cause anything to happen.

  5. The battery is only a few months old and a general inspection of the battery terminals, cabling, and fuses indicates that everything appears to be in tact and clean.

I’m not the most experienced car person, so my terminology is probably a little off and that’s all I have for now. I feel like this is a common ground issue and if I could only identify which ground services the instrument panel and radio and spark plugs I could inspect it and clean or replace a connection. My limited research reveals that there are many grounds throughout the engine compartment, though. Any geniuses out there?

Thanks! -Matt

Some simple diagnostics- Start car, tug on/wiggle main cables to battery. Does it hiccup? Turn off car, loosen battery retainer so you can slightly rock the battery itself. Start car, rock battery, see if it hiccups. Check chassis ground. It’s often on the fender next to the battery. Follow the black conductor… Check main power connection to underhood fuse panel. You may need to spend a bunch of time with the car idling and wiggling various electrical harnesses just to rule them out. I would also find the engine control computer and check the connector to that…

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I strongly suggest that you have the alternator’s output tested A.S.A.P., as the symptoms that you report are consistent with alternator diodes that are failing. By tomorrow, you could wind up with an inoperative car.

VDC, if my alternator dies, wouldn’t the car run off of the battery until the battery also dies?

Do you have like a ton of keys on the keychain? try driving it with ony 1 key in the ibnition and see if that helps

Yes, but that could be an extremely short period of time, depending on how many accessories are being used at the time of alternator failure, and–of course–depending on the condition of the battery. When the alternator on my '97 Outback died one winter morning while I was driving to work, the battery was only able to power the ignition system for about 15 minutes, and then I wound up stranded on the side of The Garden State Parkway.

Typically on a car/ engine this size you’ll get about 10-15 highway miles before the battery runs out if everything unnecessary is turned off and it’s daytime out (no headlights needed). But I strongly recommend against relying on this as a “buffer”. That’s based on real but limited experience with an alternator dying dead.

I agree with the recommendation to get the alternator load tested. As VDC said, the symptoms are typical of a failing diode. If you and your wife lack an AAA membership, now would be a good time to get one.

This type of failure often won’t store a fault code, but it wouldn’t hurt to check for a stored code anyway.

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Since your radio is not wired through the ignition switch, your intermittent dying cannot be caused by the ignition switch.

I suspect you have a bad ground problem. I had a 98 Oldsmobile that grounded the battery to the fender right under the battery. The permanent fix was to run a ground cable from the battery to the engine block.

I would start by ren\moving all the battery cables and cleaning both ends and where they mount. While you have them off, bend the cables and see if you feel wires breaking inside.

@oldimer_11 My radio stays on after I turn off the car until I open a door, so I am not convinced of your conclusion.

However, it doesn’t work that way on Subarus.
Once you turn off the ignition, the radio and all other accessories are shut down.
Subaru doesn’t use “retained power”, even though some other mfrs do use it.

Valid point…