Engine Control Lamp

[trbj]

Hi,

my excellent 2002 RAV4 seems to failing for the first time since I bought it 3 years ago. During drivin a yellow control light, the one with the outline of a engine came on. I stopped immediately and read the manual which said "drive to the nearest Toyota workshop" etc.

Since the problem did not seem severe I continued for about 250 miles and stopped the engine. When starting the engine again the light was off, however when using the car the next day the light came on again and has been on for the past three days.

Is there a way to read an errorcode and/or reset this function? How do I find a description of the procedures necersary?

[pmb]

Welcome to the forum. I have good memories from Bergen in Norway , apart from it being expensive! If you search on here you will find many reports (including mine) of the oxygen sensors failing after 5 or 6 years. Usually the heater circuit goes open circuit. The fault code can be read with a cheap OBDII scanner that plugs in just below the dashboard on the steering column side.

[trbj]

Welcome to the forum. I have good memories from Bergen in Norway , apart from it being expensive! If you search on here you will find many reports (including mine) of the oxygen sensors failing after 5 or 6 years. Usually the heater circuit goes open circuit. The fault code can be read with a cheap OBDII scanner that plugs in just below the dashboard on the steering column side.

Thanks for the nice welcome! Awfully high prices on just about everything in this country is unfortunately not limited to Bergen, - we live near Oslo....!

How do I search for the reports you mentioned? Also, I do not know much about OBDII scanners, - in fact my hope was that errorcodes could be read by shorting two certain points on a socket somewhere and then turn the ignition on and count blinks, - worked well on my previous Mercedes...!

Thankfull for any further help. If you're right and the problem is "oxygen sensor", - how much of a job and cost is involved?

By the way, is there a way to reset the indication and see if it comes up again? Disconnect the Battery for a few minutes, - might that work?

[Bodgit-fixit-run]

Use the search link at the top of this page.

Enter fault or error codes this will bring up a whole lot of links.

In Uk a fault code reader can be bought for about £50.00 from Argos. Have a look on eBay.

There are also web sites where you can enter fault codes and they will give you the correct interpretation. one such site is here OEBD2 fault code library.

I hope this helps.

Disconnecting the Battery for a while (30 mins) will help clear the code, I think.

[trbj]

Thanks for the advice. Read through everything on the topic in the forum. Deceided to try the easy way out before start spending money...!

Pulled out the two connectors, cleaned the contacts, added contact spray and reconnecred. Warning light still there. Disconnected the Battery for a while and reconnected. Warning light then off! Drove the car several times later today and the warning light never occured again. Do I have a permanent fix or is the oxygen sensor problem of such a kind that the problem comes and goes? I may add that both the two times the warning light came on I was driving long distances in very heavy rain and extremely wet road conditions!

[Bodgit-fixit-run]

Thanks for the advice. Read through everything on the topic in the forum. Deceided to try the easy way out before start spending money...!

Pulled out the two connectors, cleaned the contacts, added contact spray and reconnecred. Warning light still there. Disconnected the battery for a while and reconnected. Warning light then off! Drove the car several times later today and the warning light never occured again. Do I have a permanent fix or is the oxygen sensor problem of such a kind that the problem comes and goes? I may add that both the two times the warning light came on I was driving long distances in very heavy rain and extremely wet road conditions!

I think Anchorman might be the one to answer that one.

[bothwell_buyer]

Thanks for the advice. Read through everything on the topic in the forum. Deceided to try the easy way out before start spending money...!

Pulled out the two connectors, cleaned the contacts, added contact spray and reconnecred. Warning light still there. Disconnected the battery for a while and reconnected. Warning light then off! Drove the car several times later today and the warning light never occured again. Do I have a permanent fix or is the oxygen sensor problem of such a kind that the problem comes and goes? I may add that both the two times the warning light came on I was driving long distances in very heavy rain and extremely wet road conditions!

Its dangerous to drive whilst standing in a bucket of water

Equally, you might be able to correlate the rain with the fault ??? If not, then buy a landroevr and you soon will!!

[trbj]

Several days and many miles driven, - the engine control light still not back! A further look under the bonnet however shows four oxgene sensors rather than two. Is it a fact that some RAV 4's has two and others has four? Also, I do not understand the RAv 4.2, 4.3 etc. that frequently is beeing referred to. Which one do I own then? Mine is a 2002 RAV4, 2.0 litres 150HP, automatic, leather, sport, - even with two exhaustpipes, side and back steps and a cruisecontrol added!

[anchorman]

I think you may find that it was brought about by a very unusual or abnormal circumstance like bump starting, dirty air filter or fuel which caused the sensors to go out of range. It is possible that the sensors are starting to show a fault that will increase in frequency with time.

I have a freind with a 4.2 and his does the same; we cancel the light every now and then but it comes back.

There can be 2 or 4 sensor depending on transmission and local legal requirements.

AS we keep getting asked about the variants I have updated the post and will ask to have it pinned;

http://toyotaownersclub.com/forums/index.p...mp;#entry833883

[trbj]

Hi, - and thanks a lot for your pinned posting on variants, - very useful for us "beginners"!

The engine control light never came back. When it occured it happened in France during daily very long and intense driving. As such a very abnormal circumstance for this vehichle which usually just takes my wife to local shops and visiting grandchildren....!

However, - one thing that might be be a point: Talked to a friend who has a very similar car the other day. He had the same problem a few times and claimed that the common denominator was high Battery voltage, - i.e. Battery very fully charged all the way close up to 14.4 volts. He encountered the problem twice after having put the charger on during night and also after having driven very long distances in warm weather. He also told me that he expected the voltageregulator fitted in cars sold in the nordic countries had higher voltagerating than the standard european 13.9 (?) volts. I know for sure that other manufacturers does this for the colder climates and when importing cars privately from central european countries it is quite common to change to a highere voltage regulator as well as a larger capacity Battery!

If this was the source of my problem I should be quite happy, means that everything work properly, - the proof might be the three bulbs that was blown on the same trip, - this including the damn r.h. side parkinglight bulb that still needs changing!! If you saw my posting on the parking light bulb thing I allready refferred to high batteryvoltage as a possibility....t

[shcm]

You may be correct, but I have great difficulty accepting this explanation.

The company I work for gave up making alternator voltage regulators some years ago. I was never greatly involved with it, but I don't ever remember regulators being tested at the end of the production line and sorted into different climate categories.

With the kind of voltage differences you are quoting, I'm sure that would fall into normal production tolerances and therefore they would have to be "sorted" during end of line test. We try to avoid that sort of thing. Anyway, we almost always try to design auto electronics for one specification that covers all climate conditions the vehicle will meet.

Now, yes, I could understand a larger Battery and an alternator with an uprated output current capability being fitted , but I'm sceptical about the regulator change.

Take a look at this alternator regulator datasheet (ST are one of my least favourite auto semiconductor suppliers, but this will do as an example) and figure 4 on page 6:

http://www.st.com/stonline/products/literature/ds/11353.pdf

By using a thermistor with the regulator, the output voltage is compensated for temperature anyway, if only to stop boiling Battery electrolyte away at high temperature. In fact, with the example they give, there is about 0.4V tolerance range anyway. That will depend on tolerances in the thermistor and in the regulator chip circuit itself.

Now, with respect to supply voltage variation and the effect on the engine management ECU/check engine lamp. To begin with car power supplies are nothing like stable. Secondly, it varies with car manufacturer, but generally every ECU/System has to operate (assuming no other fault) up to at least 16V indefinitely. Then up to 18V for 1 hour or more (this is in the case of a faulty alternator regulator!) and up to 24V for 1 minute (this simulates some monkey trying to jump start with a 24V truck Battery, such as a dockside start after shipping), without damage. I don't recommend you try all of these though. :D. Some ECUs are allowed reduced functionality for things like the 18V and 24V specs, but generally the engine management has to work fully for all of these conditions.

My point is that, I can't see how such a small voltage variation that you suggest, should have any effect on the system. Sensor output voltage variation with battery supply is usually compensated for as well, by the engine management comparing the battery voltage to an accurate and stable internal reference generated inside the ECU.

I can't see a slight variation in battery voltage significantly altering the bulb life either. Disconnecting the battery with the engine running can produce a very large voltage transient (80V or more on cars), which doesn't decay for several hundred milliseconds (ECUs have to survive/work through this too). That might stand more change of blowing the bulbs. A loose battery connection can cause this, but you'll probably have problems starting the car too!

My money would also be on an ageing O2 sensor(s) (as Anchorman infers) and bulbs just coming to the end of their life. I've known more than one bulb fail at roughly the same time.

I'm not trying to cause you any embarrassment, I just can't see your explanation fitting the facts at the moment :).

Cheers

[bothwell_buyer]

shcm confirms what I kindof found out - when checking my alternator on number 1 RAV, the output to the fail-warning light was knackered, but the output charge to the Battery was around 14volts from memory and the car ran ok. Rather than fix the alternator, we changed it for a spare I had. The Battery when standing will measure around 12v+ but with alternator running, I was getting as I said around 14v.

The bulbs are more tolerant of voltage.....unless you're getting some sort of voltage spikes which shcm mentions if the Battery connection is loose.

[Bodgit-fixit-run]

I thought under normal operating conditions the Battery should be showing around 14 volts anyway. This means the Battery is charging doesn't it.

I would suspect power surges as well.

I've recently had three headlight bulbs blow within two weeks for no apparent reason. First one side then the other and then a replacement. I just put it down to being four years old and a possible duff replacement. All seems well now.

The Battery should read a little over 12v when standing to show it is charged. If it's showing 12 volts or less then it is probably flat or not holding the charge. Ther is a web site smewhere with this info on but I can't remember where.

[trbj]

Thanks for the comments!

And shcm, you may well be right! My reference to voltageregulators with different ratings is mainly from older Saab 99 / 900's and Mercedes cars during the late 80's early 90's.

On the back of the alternator there was a Bosch regulator with two carbonbrushes for the magnetization of the rotor. They looked like a good old TO-3 transistor can, fastened with two small screws, easy to take out. These regulators were available in various ratings from 13.6 up to 14.2 volts if I recall correctly. Cars sold in Germany had typically the lower end ratings, in Norway typically 13.9 volts. When the brushes were worn out one could either buy a new one at 20-25€ or go to a Bosch dealer and buy the brushes at 1 or 2€...! The regulators were also easy to modify for a bit higher voltage simply by cutting the earth connection of the regulator circuitry and reconnect via a diode "the wrong way" in order to level up the referencepoint of the regulator!

While I believe the batteryvoltage of most cars during normal operation charging is a little less than 14 volts, (to avoid loss of water on warm days), one will see around 14.4 volts while charging with a normal homecharger. In fact a fully charged Pb Battery should hold 14.4 volts, i.e. 2.4 volts per cell x 6 cells. I'd actually be suspicious if the batteryvoltage would be as low as 12 volts at engine standstill, as I would expect at least 13+ volts, preferably 13.5-13.6 volts.

Modern batteries sometimes suddenly dies after 3 years+, typically because one cell is shorted inside. Whatever you do in terms of charging you never get it above 12 volts simply because 14.4 volts less one dead cell of 2.4 volts is 12 volts! This actually happened to my RAV this spring, - but luckily after 6 good years of operation in cold climate (car is 2002 model). I use "VARTA" batteries in all my cars and it even once happened to me that one cell shorted after just a few days. Reason for it is the tighter build of the cells in modern batteries in order to maximize capacity (Ah) in limited space.

Although I might not be right about that the high voltagelevel beeing the reason for the engine control light problem, the light still did not reoccur! If it does I might well try the "15 ohms resistor methodology" that is described in another postingstring on this site just for the fun of it! Any comments on that?

[shcm]

My reference to voltageregulators with different ratings is mainly from older Saab 99 / 900's and Mercedes cars during the late 80's early 90's.

OK, fair enough. You live and learn

On the back of the alternator there was a Bosch regulator with two carbonbrushes for the magnetization of the rotor.

You used the nasty B*sch word. I'll let you off just this once (you might guess I work for a competitor :D).

While I believe the batteryvoltage of most cars during normal operation charging is a little less than 14 volts.

Yeah, I usually use about 14.2V if I'm doing any calculations (where it actually matters) .

You might be interested. The latest RAV (4.3 - the one I have), makes some attempt at a more intelligent Battery charge management. This has in the past always be considered too expensive for the benefit, but I guess opinions or cost must have changed. There's a current clamp (sensor) around the Battery neg cable, which measures charge current etc and a Battery condition ECU. To cut a long story short, the alternator voltage is also varied depending on engine load, electrical load, battery temperature etc.

Although I might not be right about that the high voltagelevel beeing the reason for the engine control light problem, the light still did not reoccur! If it does I might well try the "15 ohms resistor methodology" that is described in another postingstring on this site just for the fun of it! Any comments on that?

Are you refering to the lambda (O2) sensor heater? TBH, I think you should try to get the fault codes out of the engine management ECU, to help give some indication of the problem.

Cheers

[trbj]

Are you refering to the lambda (O2) sensor heater? TBH, I think you should try to get the fault codes out of the engine management ECU, to help give some indication of the problem.

Cheers

Thanks, - yes the O2 sensor heater! Can I get the fault codes out after having done a reset of the warning lamp by disconnecting the Battery? I.e. are the fault codes still stored??

[shcm]

Thanks, - yes the O2 sensor heater! Can I get the fault codes out after having done a reset of the warning lamp by disconnecting the battery? I.e. are the fault codes still stored??

All the ECUs (Engine/Braking/Steering/Body..........), I've been involved with the design/development of (back to late 80s) have an area of non-volatile memory, where amongst other things, the fault codes get stored. In the days of UV EPROMS it used to be EEPROM. These days it will either be part of the main microprocessor FLASH memory or again EEPROM.

People claim you can reset the MIL (malfunction indicator lamp), by disconnecting the Battery and probably you can.

However for all our ECUs, the codes will still be stored even if power/battery is removed. They have to be cleared manually. For one thing, if we get units back under warranty return, it helps diagnose the fault (i.e. if it is really our ECU that has failed), as it's fairly impractical to ship a unit back to an ECU manufacturer with a Battery connected!

Maybe Toyota do things differently. Perhaps they never ever get a faulty ECU or system, so they don't need to diagnose a problem!

If you are able to try to read out a code, why not give it a go? If it has lost it by removing the power, then clearly they don't store the codes, and obviously you'll have to wait until the light is on again.

Cheers