2003 I35 Electrical Weirdness?

[adamsusa]

Ok, have a 2003 I35 with 140K miles. Two days ago, was pulled over on side of road for a work phone call with the engine running for about 10 mins. Went to roll up the window but nothing happened. It was warm (89) so started the AC. Then decided to turn engine off. Went to start 5 mins later and no go. Turning ignition on, all dash lights go on, but when starting motor dash lights when out and starter wouldn't engage. Starter made clicking noise, like when the battery is low.



Thinking it was a low battery (even though engine was running for all but 5 mins), can someone to give me a jump about 30 mins later. However, before even connecting cables, car started like nothing ever happened.



Next day, run one errand (5 mins away) no problem. Go to run second errand (another 5 miles away), but car again wouldn't start afterwards. Like before, window wouldn't roll up, dash lights go out when trying to engage starter.



Few minutes later, try it again and car starts. However nearly all warning lights are on (recall specifically the Check Engine, ABS, TCS, and even Airbag light). Put car into reverse and car moved slowly - put in drive and throttle effectively was disabled. Car was moving forward, but only at engine idle speed. Tried again, was able to drive 1 mile before throttle became unresponsive.



Next day returned to car with OBD reader. Nothing reported (very surprised). Measured battery voltage - very low (9.6v). So charged the battery with a jumper again. After 10 mins battery is fully charged ready to go. Was able to drive it 4 miles home without a problem.



Thinking this was a charging related problem, did a visual inspection of the battery. No problems observed; water fine; connections clean; battery only 2.5 years old (not new, but not "old"). Suspecting an alternator problem, have my son rev engine to 2K RPM and disconnect the battery. Within seconds, engine dies. Huh, so possibly the alternator. However, pulled the alternator and it bench tested fine.



So, I'm confused, puzzled and a bit frustrated at this point. Looking for any suggestions. Thx in advance.

[NutriaforBreakfast]

See what the battery reads while the car is running
The FSM should have a spec for voltage

[loystock]

With so many on-board computers/controllers in newer cars, it's not a good idea disconnecting the alternator as a voltage spike can damage the controller(s). That practice works in older carbureted cars but not recommended in newer one. So something is preventing your battery from getting fully charged. Anything lower than 12 VDC is considered a 'dead' battery. A fully charged battery should have 12.6 VDC or higher. So if the alternator is good, then you may have a partial short to ground. Check the battery cable and alternator harness for 'crossed' wires. It's also possible that one of the power rectifiers in the alternator has gone bad. A good alternator should have a steady output of >13.8 VDC (spec is 14.1-14.7 VDC). If you cannot find a partial short in the system, then the alternator is on the way out.

[adamsusa]

Update - still have the same problem, but have a better understanding. Here's what's been done:

1) Battery failed bench test (3 years old). Replace with new one.
2) Alternator passed bench test.

After reassembling battery & alternator, ran car with headlights and accessories one. After 15 mins, engine died. Appears charging system still not functioning. Battery with engine off = 12.8V, with engine running (zero minutes) 12.1V. After 10 mins, with engine off 12.1V with engine running 11.4V. After 15 mins, engine off 11.8V, engine running 7.8V.

Where should I look next?

[NutriaforBreakfast]

Check ground wires on the engine

Make sure battery cables are tight and clean

Sounds like an electrical drain. Never have done it but if you have someone help
you pull fuses while you use a multimeter on the battery you should be able to find it

[loystock]

You have a short somehwere. Disconnect both battery cables and measure resistance across them (not the battery). A normal electrical wiring will normally read in the Kilo-ohm range and beyond. You can also check the current flow with engine/accessories off. Reconnect the + battery terminal and then use an ammeter in series with the - terminal to engine frame. A normal parasitic current should be 10mA or less (due to clock, ECM, etc.). And just like what 'nutria' mentioned, you can disconnect one fuse at a time to find the faulty circuit.

[adamsusa]

Update #2: Problem appears to be intermittent. Charged battery, measured voltage; 13.2V at battery engine off - good, fully charged. Drove to local shop to have charging system inspected. They connected tester and alternator was putting out ~14V (measured at battery). In disbelief, I took my same voltmeter used to observe the draw down and yes, it measured 14V.

Went hope and measured again with engine running. Low and behold, now only 12.1V.

How likely is the Alternator to be intermittent like this? Haven't started looking for potential shorts, but will do so next.

[NutriaforBreakfast]

Maybe the voltage regulator within the alternator is going out?

[the converted]

I had a somewhat similar problem with mine a while ago. The brushes in the alternator would work intermitantly. I had it rebuilt, and was told that oil got into it and killed it. Mine was an oil burner, and I was adding a quart every 1k. The little spillage was channeled perfectly into the alternator.

[adamsusa]

"The Converted" - I think you might be onto something there. I did notice a moderate amount of oil/grease buildup on the alternator housing exterior. Considering it has 140K miles, didn't think much of it. I did wipe it down a bit after it was removed. So I could see how oil/grease could interfere, resulting in the intermittent nature.

I just tried to find a potential short by checking fuses, but the "drain/no charge" stopped 1/2 way through it. Nothing worse than trying to fix intermittent problems.

[NutriaforBreakfast]

Loystock,

Do you think it would hurt the alternator to spray mass airflow cleaner into it
to clean it out? I works on my motor of my electic chainsaw

[adamsusa]

For lack of other cleaner, I did spray it with brake cleaner. It's been two days and after about a dozen checks, haven't seen the charging problem. That being said, really don't want it to crap out on a road trip of something like that. So, I've ordered a new one to replace with, for piece of mind.

[NutriaforBreakfast]

I had mine rebuilt for $79 at a small shop. They told me the guts of the
original alternator were better than one bought at Autozone, Oreilleys etc

[loystock]

That's true. One time, I was in a hurry and bought an alternator from Kragen/OReillys instead of OEM or rebuilt. I verified there's no short in my car yet the 1st one failed as well as the warranty replacement. Only on the 3rd alternator did my car finally worked. And it's no fun changing these alternators.

[adamsusa]

Since it's always good to hear how a issue was resolved, I replaced the alternator with a rebuild from a local shop and all is good now.

Thanks everyone for your responses.