2003 Rav4 Problems

[Blown364]

Hi All , I have a friend who is having problems with his 2003 manual Rav4 , the speedo is working but bounces/fluctuates up and down bad , about 10 mph ether side of his speed .

I was hoping someone could tell me if the speedo has a speedo gear in the trans or does it use a signal .

He has been told that it needs the engine and trans taken out and the transmission needs to be taken apart to fit a new gear in it for the speedo , cost to do the job was Aus$4800 around 2500 pounds .

Any help would be very welcoming .

[CharlieFarlie]

I would have thought it uses a signal but for not a lot of coin he could get one of those GPS based speedos ??

[Blown364]

I am thinking the same thing , waiting for a scope to get a look into the box so I can see what is going on also . I told him to fit a Sat-Nav , he wants the speedo working . If I need to take the engine and box out then pull the box apart I'm not interested in doing the job.

[Pogle]

There is an electronic speed sensor located on the top of the transmission which sends info to the ecu. Possibly sends it to speedo as well?

[Davrav]

It's worth checking connections to back of clock unit for contact, or lack of it, due to corrosion/damp

[Tech01]

Yes, the "vehicle speed sensor" is located on top of the transmission. This is a Hall Effect sensor which sends signals (pulses) to the ECU and instrument panel. The frequency of the pulses is converted to a rising voltage (F to V converter), which feeds the speedo (which is a voltmeter).

Check connections at the sensor, the ECU, and the instrument cluster/speedo.

(If you have a cruise control fitted, then it also derives its "speed" info from the VehSpeedSensor, so if the cruise works OK, then the sensor is OK too.)

Most likely a poor connection somewhere, if intermittent.

Chris

[Blown364]

Thanks guys been a big help , It has had a new sensor fitted to it and worked for about 10miles then went back to reading erratic . I felt it didn't have a gear and a used pulses .I have heard that the drive/gear on the shaft can come loose and if that's the case is easer to just get a second hand box ?

I will go and have a look at it over the weekend , I am only going on what my friend has told me .

Again thanks .

[Tech01]

"I have heard that the drive/gear on the shaft can come loose."

If you are able to get hold of an oscilloscope, then you could check the stream of pulses from the VehSpSensor, to see if it's intermittent or wandering. Otherwise, it's off to Mr.T to run a diagnostic check on the same.

Chris

[Devon Aygo]

In all the years I have worked for Toyota I have yet to see a faulty speedo drive, I have however seen more than a few Rav's with water ingress into the RHF wiring harness behind the kick panel to the right of the throttle pedal. If you remove the trim there is a large harness junction behind it, one of the connectors there is held in with a bolt through the middle of it, remove this plug and check for corrosion to the connectors. clean/repair the connector then check the speedo. If the fault is cured find the water ingress point and fix that to stop the fault coming back

[Bristim]

I had something like this about a year ago on my 2003 RAV4, except it intermittently took the speedo out completely. I checked on here and RAV4World before doing anything and identified that moisture or a poor connection might be the cause - just as described by Devon Aygo (except confusingly with 'the other site' being 'merican they talked about the panel being on the passenger side).

I remembered leaving some wet kit in the car and it turned out to be some sort of weird condensation going on - basically once aired and dry the problem seems to have disappeared without a penny spent.

I would check this wiring loom before doing anything else and it has reminded me that I wanted to check it on my car too - it seems to be a reoccurring problem from the number of times it seems to have cropped up online.

[Blown364]

Thanks for everything , I felt it wan't in the box , the more you all tell me about the problems with corrosion the more I am sure thats going to be the problem , Living in the wettest town in Australia we get our fair share of rain at around 16ft a year .

I will try to get a look at it soon and let you all know how it went . Thanks again .

[Blown364]

Well I got the Rav4 today , fist time I have seen the peoblem , When you drive it the speedo sometimes will not move then jumps up to about 10mph , it will sit about 15mph slower then the sat-nav , I got to 60 mph by the sat-nav but it still only sat on about 40mph on the dash . Sometimes you can come off the throttle for a few a sec and the speedo moves up a bit but as soon as you get back on the throttle if drops down again , only a few mph .

I took the sensor out of the back of the box , (5 speed) . Its got a speedo gear in it . I used the scope to get a look at the gear in the box and all looks good , no marks on it at all . I have taken the dash out and still can't see anything wrong with the wiring , also have looked at the wiring beside the throttle and unpluged them all but again nothing , I will still clean them all .

Something I did find very strange was the tappet cover on the engine looks like it has corrosion on it , well its more like someone has put acid on it and part of the cover it black and eaten away , never seen anything like this before. Just thinking if there is a problem with the ground on the engine/car could this be the problem with the speedo and whats going on with the tappet cover , if i can get a picture and get it in here I would love to know what you guys think .

[Blown364]

Got a chance to look at the Rav4 , first I must say its not a 2003 but 2002 ,2Lt , The speed sensor is at the back of the box .

I took it out and its running a gear . Got the scope into the box and the gear in the box looks fine , Looked at the wiring in the car and again all good , I then went back to the gear in the box , got a long scriber and found the gear is slipping on the shaft , not good .

I think I have talked the guy into fitting a GPS Speedo . Just a big job to fix a 50c problem .

[toy car owner]

If it worked for ten minutes then when back to its old ways you could have connection issues at the sensor, try a drag test which requires removing the female terminal from its housing then connecting it to the sensor, there should be tension as you push/pull the terminals together/apart. Loose terminals will cause high resistance the will increase as the temperature rises.

[Blown364]

^{Hi Jason , I am 100% sure its not a connection problem , I found the speedo gear in the box is slipping on the shaft , I can turn the tail shaft and look at the gear turning with my scope but as soon as I put something on the gear to try to stop it from moving it just slips on the shaft , everything still turning but I can hold the gear in place with a bit of force , I think what is happing it the gear make contact with the sensor for a while until it starts to move away for the sensor gear , nothing to stop it from moving on the shaft , I can move it about 10mm but the look of it on my scope .}