Weird problem - no start, showing -40*F

[oldskewel]

Weird problem today, trying to start my 2001 3.0i with 183k miles, running well ...

Turning the key just gave click-click-click (loud, stong clicks). No actual attempt for the starter to turn. No start.

Repeated this at least twice. Maybe 3 times with the same result.

Weird. I figured someone had left a light on and run down the battery, so I searched, did not find anything. Checked battery voltage at the jump points in the engine bay, with a voltmeter = 11.7V = plenty good to start.

Back in the seat, the green LED for the AC was on, so I pushed the AC button to turn that off. Turned off all HVAC controls too. Turned off the computer screen thing.

Tried again and it started right up, everything looking great except it tells me the temp is -40*F. Idles fine. Shut it down, restarts just fine, still thinks it's -40*F.

My son then wanted to borrow it for a ~10 mile round trip to go running (yes, drive 10 miles so he can run 10 miles in the hills; so I figured if the car stranded him, he could just run a little further). When he came back, he told me the temp was displaying as -37*F.

No problems at all before this. Nothing weird.

Any ideas? I am pretty certain the -40*F is related to the failed start.

BTW, it was probably about +60*F at the time.

Thanks!

[Crowz]

Ignition switch is probably on its way out.

Mine did the same thing when the voltage got down to 12.2 or lower. Above 12.2 and it fired up everytime.

The only strange part is what normally happens is it will do nothing when you try to start it when messing up so you may just have a loose wire at the starter instead.

Hard to diagnose stuff like that remotely over the net and all.

I would check for loose starter wires first and if they are fine I would do the ignition switch if it was me.

[oldskewel]

Would either of those faults cause that -40*F display?

Also, I know it could have been coincidence, but when I turned off the AC and HVAC stuff and shut down the monitor display, it worked after that.

[Crowz]

Turning things off raises the voltage available which is usually the ignition switch.

The -40 basically is the computer jammed up. I imagine disconnecting the positive battery cable in the back for a few minutes and reconnecting will straighten that out.

That or you have wiring issues on the temp harness which would be weird for that to mess up at the exact time the other was happening.

[tempest411]

Believe it or not, 11.7V is a pretty dead battery. There's a good chance the voltage plummets as soon as you try and crank it.

[Crowz]

Originally Posted by Crowz

Turning things off raises the voltage available which is usually the ignition switch.

The -40 basically is the computer jammed up. I imagine disconnecting the positive battery cable in the back for a few minutes and reconnecting will straighten that out.

That or you have wiring issues on the temp harness which would be weird for that to mess up at the exact time the other was happening.

Agree on the person that borrowed it ran over something and damaged the temp sensor. I was under the impression that it suddenly went -40 after the cranking issue is why I mentioned disconnecting the battery.

Definitely the sensor and or wiring since it happened separately.

[CapeX5]

the temp reading is unrelated. That is usually indicating the outside temp sensor and its wires has been ripped out of its location in the front right bumper underneath. Look on realOEM for part numbers.

[80stech]

Taking voltage readings without a load is going to lead you down the garden path. Even the battery voltage chart only indicates "state of charge" which only tells you when a known good battery is fully charged.

[Qsilver7]

Originally Posted by oldskewel

I am pretty certain the -40*F is related to the failed start.

BTW, it was probably about +60*F at the time.

Thanks!

Ditto the replies above in regards to the ambient air temp sensor. I highly doubt it is the culprit of a "no start" situation. Seeing -40°F in the display is only a symptom that the ambient temp sensor has failed in some way...aka the wiring has been damaged or the temp sensor has failed in some way.

I believe it sends data to the DME...which is then shared with other modules like the IHKA & IKE & GM to regulate some of the IHKA's programs, display the temp in the cluster, and to actuate the heated mirrors & washer jets. But there's nothing about the ambient temp sensor that would stop the vehicle from starting.

[oldskewel]

Thanks for the ideas.

My daughter took it for an uneventful drive last night.

Figured I'd look into it today...

First thing, battery measured at 11.96V (as before, this at the jump ports in the engine bay)

Key in, to ON, shows 59*F. So unless someone snuck in and replaced my temp sensor last night ...

Carefully turned off all the HVAC and computer monitor nonsense that really wants to be wanted.

Try to start - click click click, instrument panel and computer monitor flashing, turning on, off, etc.

Repeated a few times, same result.

Battery read 11.5V after those attempts.

Hooked up a battery charger, ran it on 10A for a couple of minutes. No help. Got impatient, so I pushed the switch to the 50A engine start and it started just fine. Makes sense, if the battery is marginal.

So now it is parked in my driveway, getting a long, patient 10A charge.

=================
My thoughts so far:
That -40*F was probably the computer getting jammed up just like crowz thought. I had wondered if -40*F might instantly provide the answer, being such a specific clue. Guess not.

11.7V might be a weak battery in this case. I often have no problems with voltages in that range on cars, but this is more of a computer with wheels.

The battery is almost 4 years old, with a Feb 2014 sticker on it.

This car takes lots of pretty short trips, so it is entirely possible that the battery will live a little longer with some periodic full charges. I'll test this out and see how it goes.

Hopefully the solution will either be to keep the battery charged better, or to just replace it, and nothing more than those.