Thread: Numerous failures, but could it be an ECU error?

Check the battery voltage?,did you recently replace the alternator?,did the errors start before or after that job?. Pat

Hi Pat and I think the battery is OK and I get 14+v at start up so thats not a problem.

BUT, as you posted, everything has only happened since the alternator was replace so maybe a reset is due.

While the alternator was replace at least 6 months be for the transmission started it’s little games, I have not been able to get into the hidden screen since the alternator was replaced and I did not put two and two together.

Thanks for the suggestion.

DS, I was getting the “MAXIMUM SPEED 50 KMS” message when my battery was on the way out. Alt was fine, I think it was because the V dropped too far during engine start, and this 'fault' is one that doesn't try to reset itself untill the car is turned off/on. New Battery, not seen the message since, may not be you issue, my EAS wasn't in a "not enabled" state though - just a thought.

Originally Posted by drivesafe

Is it possible that there are no actual faults and the problem lays with the ECU?

Its likely that a simple fault such as low voltage at a critical time has triggered a fault condition in 1 ecu that has triggered flow-on faults in associated ecus. The gear train and suspension are closely tied by TR so a fault in any component is likely to generate faults in other systems. This doesn't help find the cause though!

Thanks harlie and an interesting suggestion because my battery was discharged down to 7v in a few minutes when the alternator went and I honestly gave it little hope of being able to be recharged, it but it came good.

Thing is, maybe it just gave me a bit of time and is now at the end of it’s usefulness and your suggestion maybe the cause ( it is the original battery ).

Thanks Graeme and this is an area I have not worked in but it looks like it’s time to start.

The plot thickens with my RR.

To day, after days of suspension fault warnings of different types, suddenly the fault messages ceased.

Until I tried to lower the RR and back they came, so I will see how many days before they stop again.

Originally Posted by drivesafe

Until I tried to lower the RR and back they came, so I will see how many days before they stop again.

Yeah, remember in the digital world of 1s & 0s the voltage doesn’t have to be down much for a 1 to be received by the next ECU as a 0, and then it's all gone to pot. The sensors and switches are anologue but comunication between ECUs is digital and very sensitive to voltage. Try a battery, at $200ish, it would have to be the cheapest thing to start with too - not to mention being original it's time is nearly up (from memory you have a '07?).

Surprise, surprise.

I have been keeping an eye on my cranking battery since the alternator crashed.

At the time I was surprised the battery actually recovered from the 7v rapid discharge.

Since then I have measured the voltage on a regular basis, taking the measurements at least 12 hours after the last drive.

The measurements have always been 12.35v or higher but this morning, after 48 hour since the last drive, I got a reading of just 11.84v.

The battery is stuffed and to confirm this, I tried recharging it and after just 1 hour, using a 16 amp charger, the battery charger was indicating the battery was fully charged.

NO WAY.

So a new battery on Tuesday and will see what goes from there.

I’ll see if this resolves the problems BUT, do I still need to have all the fault codes cleared and will this happen automatically?

If you still have the suspension not active message and the lights are out on the suspension control, unfortunately you will need the faults cleared.

It's a stupid system that 'thinks' there is a problem (can be as simple as a dropped or misinterpreted packet) and doesn't retry...