ECU reset & test mode not working

Started by Guest_KONG_* , Feb 25 2016 05:44 AM

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#1 Guest_KONG_*

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Posted 25 February 2016 - 05:44 AM

Hi guys, I'm hoping to get some advice from the sparky gurus here.

I'll try to keep this short and sweet.

I have a CEL light and after scanning there were 2 codes found.... The Cam sensor and front O2 sensor.

The Cam sensor itself was checked and turned out to be OK. The Cam signal at the ECU was also checked by a sparky and one of the wires had no signal. I'm aware there are 3 wires at the ECU for this sensor, positive, negative and a shield.
I personally have no idea what a shield is or if it should've or even needed to have been checked at this time.

I haven't checked the O2 sensor as of yet.

Now, when I connect the black test plugs the engine light flashes and functions normally and I can retrieve CEL codes.

However, when I begin the reset mode & connect the green plugs, the test mode cycling of fans and solenoids etc doesn't happen.

When the engine is started the CEL light remains off and doesn't flash as it's supposed to under normal reset conditions.

The cluster bulb is obviously in working order.

Has anyone heard or experienced anything like this before?

It seems there is a wiring issue with test mode along with the Cam sensor and possibly the O2 as well.

Do these 3 sets of wires share a common denominator??? or circuit or junction or earth perhaps?
They all share the same plug at the ECU.

Is there anything I could investigate before heading off to an auto electrician?

Or does anyone have any information I could pass on to the electrician that may assist them in order to lubricate my wallet before it gets raped.

Keep in mind I am a forking retard when it comes to electrickery, so if you have any information that may help please word it like you are advising someone who has brain damage.

Any help would be appreciated,
Cheers.

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#2 duncanm

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Posted 25 February 2016 - 06:45 AM

test connector looks like it goes straight to the ECM -- maybe check at the other end that it's ok.

Similarly, the O2 sensor loom has no plugs between sensor and ECM.

The crank, cam and knock sensors share a plug -- sheilds should only be connected at one end, and must be open at the other end.

I've attached the engine wiring diagram I have for a B4.

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#3 Guest_KONG_*

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Posted 25 February 2016 - 12:17 PM

Cheers Dunc, I'd love to have a beer with you some time.... BOOM!

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#4 Robbks

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Posted 25 February 2016 - 01:23 PM

For a reset are you Keying off,
Connecting Black and Green,
Then IGN to ON
Depress Throttle to 100%, hold for a second or tow
Release throttle to 50%, hold for a couple of seconds
Release throttle
Start car, and drive until the CEL flashes constantly (over 11km/h i believe is the correct way, But I've only needed to do it for a few seconds up the length of our street (200m) in my forester and multiple Liberties/ Legacy)

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#5 Guest_KONG_*

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Posted 25 February 2016 - 01:46 PM

Yes Rob, I have the procedure down pat, from years of owning TT's lol.
The CEL light just doesn't flash at all at any point during the reset process. It simply just doesn't light up.... The solenoids & fans don't do their cycling test when the plugs are connected either, which is weird.

I'm probably way off here, but is it possible the wiring problem I have with the Cam sensor could be causing this?
Or am I just thinking too much.

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#6 WillC

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Most things with a pulse. Most things that tick and have electric.

Posted 25 February 2016 - 02:54 PM

Have you used a obd2 tool to reset it yet Kong ? my codes on the B4 wouldn't turn off until I cleared the ecu memory with a OBD2 tool.

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#7 LukeFranky

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Posted 26 February 2016 - 08:41 AM

As you know I had a cam shaft sensor issue. Did lots of tests on it. Sensor checked out.

The resistance in the cabling was troublesome so I replaced the whole lot from the ECU to the sensor with heavily shielded cabling from Bunnings and even retro fitted a new plug from some other sensor. This isn't hard to do and did improve my symptoms but not totally.

My bluetooth OBD2 scanner kept registering voltage drops in tune with the flickering CEL, as low as 10.5V with headlights on. I bought a cheap aftermarket alternator off Ebay (sounds terrible doesn't it) and swapped it over when I did my timing belt. I have not seen an engine light since and throttle response is much better. According to my scanner the voltage still gets into low 11's and doesn't even charge as high as the old alternator but my guess is it is supplying a more stable cleaner current.

The B4 Bomber - 2002 MY03 Subaru Liberty B4, ADM, Manual, EJ208.