08 Aveo - shut down while driving - no start

The symptoms that have happened are VERY much in line with those in this thread: Unfortunately the OP has not returned to post a solution (if one was found) - [ Scratch that - I contacted him and HIS fix was a blown DIS (10A) fuse. Not my fix, though)

http://www.aveoforum.com/forum/f82/no-spark-22155/

My daughter was driving 2 days ago on the highway, and the car simply shut down. She was able to coast to a safe spot in a parking lot off the highway.

What I know so far:

-2008 Aveo LT
-As far as she can recall - the CEL came on first before all the other dash lights came on like a christmas tree.
-Engine turns over with key - but does not try to even sputter as if it were trying to ignite fuel.
-Starter fluid sprayed into the intake does not ignite. (It kind of coughed once - but not on subsequent tries)
-Fuel rail IS pressurized
-Pulled the cosmetic cover from the engine - and timing belt is in place and feels "okay" to the press of a finger.
-Coil secondaries both measure equally at 5.6k Ohms. Have not measured primaries yet.
-Battery was dated 12/14 had no charge. I did *not* try to charge it - given our Texas heat - I opted to go ahead and replace it. (It had some slight swelling to the battery case).
-New battery makes no change in the situation so far.

What to try?
Thanks,
Rex Smith
Richardson, TX

Update 1 - I was able to contact the OP of the thread listed above - he mentioned to me that he changed a 10A fuse labeled DIS - and that fixed his problem.

So - I checked all of my under-hood fuses. There was only 1 blown - and it was labeled: EMS1 (15A).

I replaced the fuse - and lo-and-behold - the car fired up. After about 30 seconds the CEL light came on (I don't have a reader - so have not ran the codes yet - will do ASAP)
It ran for about a minute - idle then jumped - and it started running VERY rough. I got out to check under the hood (with it still running) - and noticed about every 6-8 seconds it was backfiring through the airbox.

I got back in the seat - gave it a little "goose" to the throttle to see if it would even out - and it died.
And, of course, the EMS1 fuse was blown again.

Upon another search - I found a poster who mentions that the EMS1 fuse runs:

Quote:

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i looked at schematic for the ems1 fuse it feeds the anti theft ecm,vehicle speed sensor,high low light relay,abs module,ac relay. It sounds like you have a short or even a bad ground would cause the amps to go up and blow the fuse. Myself i would look for any pinched wires from the engine installation. and check your grounds that fuse feeds alot of circuts. Have your mechanic look up wire schematic

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Now, the engine swap pinched wires doesn't apply here - however - with this vehicle being an '08 - can anyone verify EXACTLY what all is controlled by this fuse? (Schematic scan that might be able to be emailed to me off-list?)

Thanks,
Rex S.

After borrowing an OBD-II scanner says:

P1516 - Throttle command/actual throttle position -signal variation Wiring, throttle valve sticking, throttle control module
P2105 - Throttle actuator control (TAC) system - forced engine shut down mode Wiring, TAC motor, APP sensor, ECM
P2106 - Throttle actuator control (TAC) system - forced limited power mode Wiring, TAC motor, APP sensor, ECM
P2110 - Throttle actuator control (TAC) system - forced limited rpm mode / Heated oxygen sensor (H02S) 1, bank 1 - implausible signal Wiring, TAC motor, APP sensor, ECM / Wiring, short to positive, short to ground, H025, ECM

So - It's probably somewhere in the throttle system... in addition to other possibilities - the last code indicates a possible wiring short - which may indeed be blowing that fuse when I touched the throttle with my foot. More diagnosing in the morning with daylight on my side.

Any thoughts from the Aveo gurus?

Try removing both cooling fan relays, replace the EMS1 fuse, and see if it will run for a while without blowing the fuse again.

I'll try that tomorrow. We did go ahead and order a new Throttle Body assembly - which is supposed to arrive tomorrow - and hopefully fixes the problem - but as mentioned - I'll try the relays before the swap.

Quote:

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Originally Posted by avguy

Try removing both cooling fan relays, replace the EMS1 fuse, and see if it will run for a while without blowing the fuse again.

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Quick question - When I ordered the Throttle Body - they recommended that I order a new wiring harness with pigtails that have to be spliced into the old wiring. The TB and harness just arrived - I've got the old TB off... and curious as to whether there is an opinion as to whether I should preemptively replace the harness as well - or wait til I see if the TB itself fixes my codes. ?

(And that new darned harness' wires are all the same color! Arrgh!)

Thanks,
Rex S.

Okay - after replacement and relearn procedures (done several times) - I'm still throwing these codes:

P1516 - TAC Module Throttle Actuator Position performance
P2106 - TAC System - Forced Limited Power
P2110 - TAC System - Forced Limited RPM

During the relearn procedures - it still wanted to backfire through the airbox several times.

What else do I need to look for? Could this be symptoms of a timing belt that has gotten off by a tooth or something? (We are contacting the previous owner to see at what mileage the timing belt was changed last)

(AVGUY - I just pulled the fan1 and fan2 relays - and when I started the car - it threw codes for those 2 cooling system relays)

Then when I touched the throttle - I got P2105 - for forced engine shutdown in addition to the codes listed above - but did not burn out the fuse

Frustrated in Texas....
Rex s.

My first suspect would be that the original shutdown was due to a short-to-ground in one or more of the circuits that are protected by the EMS1 fuse. So, after visually inspecting the wire bundles and connectors, particularly in the area of the exhaust manifold, I recommend starting the diagnosis by checking continuity on every wire of each circuit in the EMS1 path. Slow process, but will eventually lead to the culprit.

That's kind of what I was thinking as well. I'll need to find a reliable schematic so I know what wire is supposed to get what signal.

A mechanic friend (out of state) suggested I go ahead and take it into a shop that has a true diagnostic computer (not just a code-reader) and see what signals may be being sent to the throttle body - thinking (without seeing the car) that there may be a possibility of a pooped out computer circuit, physical wiring problem, or something wrong with the accelerator pedal (and it's circuitry) itself, since the car goes into shutdown mode when the accelerator pedal is touched - and also never does truly find a proper idle with the new TB installed.

The backfiring through the airbox - he indicated was an indication of too much fuel - but he didn't think it was a timing belt issue - because other codes would be thrown.

(Also - the previous owner has a receipt from the dealer changing the timing belt, tensioner, and water pump at 117,000 miles (the car has 137,000 on it now) - so it's unlikely to be a timing belt problem)

I'll do what I can before taking it in....

Thanks for the suggestions - If more come to mind - please post. I'll follow up with my findings.

Rex S.

Does anyone here have a diagram they can point me to for the throttle-body wiring harness pinouts on the 2008 Aveo LT 1.6L? Our harness has 8 pins (2 rows of 4) The top row is fully occupied with wires, the bottom row only has the outer edge pins occupied with wires. Unfortunately my local library does not have an AllData subscription.