Ecu (the Computer In The Engine)

[Ste1983]

Hi Everyone,

Had my Aygo from new (55 reg)but the past few weeks the powersteering in my car has been acting up. When I first started the car I had no powersteering for the first 5mins. After a week or so I started to get a light on the dash so took it to the Toyota garage I bought the car from. They had a look and told me the ECU has a fault and it would cost about £230 to fix.... ontop of this got to add labour (about £65ph) then vat so it all adds up to a rather pricey sum.

Oddly tho one of my friends is a mechanic and says that this is a known issue with Aygos. Has anyone else had this problem? If its a known issue surely Toyota should be looking into it.

I love it but so much has gone wrong........ new radiators, new engine bracket, new steerin bracket, new brake system, the car squeeks and can't seem to be fixed, it leaks ........................ ARGH, new car time maybe!

Thanks!

[adilmon]

The car's ecu will cut power to the electric power steering if the car's Battery is low. It's a failsafe. After all, there's no point having power steering if there's not enough to run the engine properly. Once you start driving and the alternator charges the Battery a little, then the power steering comes back on.

It sounds like your garage can't be bothered to read the repair manual (it's long but interesting) and execute proper trouble shooting. A low Battery will not show up as an ECU diagnostic trouble code (DTC), so that's the most likely senario you have.

Get a fresh battery, or go to Halfords and get them to use their Bosch scanner to tell you the exact condition of your current battery. They can tell you percentage charge left as well as just the voltage

[Ste1983]

Thats really interesting and great advice - thankyou very much! I'll pop into Halfords ASAP. :)

Cheers again mate

[adilmon]

You're welcome. Let us know what happened next. If they still decide to change the ECU, get the DTC from them first and I'll look it up for you. It's worth noting that there have been no Service Bulletins issued for the ECU.

[Ste1983]

Not sure if it makes sense but they told me "c1552" - is that an error code or............I'm not very mechanically minded

[Jan van de Wouw]

C1552 comes back as "Power Source Drop Voltage Malfunction" when I look it up on-line and all codes I can find

about that regard EMPS (Electric Motor Power Steering), so Adilmon's first guess was probably correct: low Battery...

[Ste1983]

Thanks Jan.

Rather p**sed off if a Battery charge/new Battery would fix it when the garage told me other wise.........

trip to Halfords this weekend!

[adilmon]

Thanks Jan.

Rather p**sed off if a battery charge/new battery would fix it when the garage told me other wise.........

trip to Halfords this weekend!

C1552 is a clearly listed code on the Toyota power steering failsafe chart. I would seriously bend their ear about trying to sell you a story about a faulty ECU. That's why I bought a SCANGAUGE II. So I can see what the ECU sees. It's a shame some mechanics abuse the customers' trust and fob them off. If you had changed the ECU the problem would still remain.

Note. voltage should be at least 12v and charge at least 50%.

[adilmon]

If the garage is still to lazy to do the troubleshooting correctly, here's the procedure for your DTC:

INSPECTION PROCEDURE

1. READ VALUE USING INTELLIGENT TESTER

Check that PIG POWER SUPPLY in the DATA LIST is between 10 V and 16 V.

OK

INSPECT FOR SHORT CIRCUIT IN HARNESSES AND ALL COMPONENTS CONNECTED TO EMPS FUSE

NG

2. INSPECT FUSE (EMPS)

Remove the EMPS fuse from the engine room R/B No.1 and J/B No.1.

Check the resistance of the EMPS fuse.

Standard Resistance:

Below 1 Ω

Reinstall the EMPS fuse.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU ASSEMBLY - BODY GROUND)

Disconnect the C24 connector from the power steering ECU assembly.

Measure the resistance between terminal PGND of the C24 connector and body ground.

Standard Resistance:

1 Ω or less

Reconnect the connector.

NG

CHECK FOR INTERMITTENT PROBLEMS

OK

4. INSPECT FUSE (ECU-IG)

Remove the ECU-IG fuse from the instrument panel J/B.

Check the resistance of the ECU-IG fuse.

Standard Resistance:

Below 1 Ω

Reinstall the ECU-IG fuse.

NG

INSPECT FOR SHORT CIRCUIT IN ALL HARNESS AND COMPONENTS CONNECTED TO ECU - IG FUSE

OK

5. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU ASSEMBLY - INSTRUMENT PANEL J/B)

Disconnect the C23 and C24 connectors from the power steering ECU assembly.

Turn the ignition switch ON.

Measure the voltage between terminals IG and PGND of the C23 and C24 connectors.

Standard Voltage:

10 to 16 V

Reconnect the connectors.

NG

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

REPLACE POWER STEERING ECU ASSEMBLY

[zakelwe]

Hold on a minute, wouldn't the car be hard to start before the Battery got so low the ecu cut out the power to the powersteeting, you'd have to think that starting the engine requires a lot more juice than assisting the wheels and therefore the engine turning over more slowly on the starter would be the giveaway ???

Regards

Andy

[adilmon]

Hold on a minute, wouldn't the car be hard to start before the battery got so low the ecu cut out the power to the powersteeting, you'd have to think that starting the engine requires a lot more juice than assisting the wheels and therefore the engine turning over more slowly on the starter would be the giveaway ???

Regards

Andy

Maybe true, unless the alternator fails. The starter motor is more sensitive to a drop in Current, whereas this failsafe refers specifically to voltage drop. Typical voltage is 14.4v with the engine on. That's also why the trouble shooting is concerned with checking the electrical connections. Checking the Battery is the cheapest and easiest thing to rule out first.

[Ste1983]

Well still not got to Halfords (work etc.) but will do tomorrow......

I have noticed that my car has been fine for the past few days - its been warm and dry. This fault started when it was snowing.............

Weather causing problems?!

[Ste1983]

Just back from Halfords and the news is..............

The Battery is fine. Its just over 90% charge when cold, when running with fans, radio, lights etc. on was fine and alt was charging it up ok.

Its good news for the Battery but not good about the ECU :(

[Jan van de Wouw]

I think you're worrying too much.

The car is fine now and who is to say the error will occur again?

A lot of things could have caused the fault to arise, maybe even a

bunch together like cold weather and running a lot of short journeys

with a lot of electrics on and then parking the car for a couple of days.

IMHO you only have reason to worry if the error occurs again within a couple of days.