Speedometer fluctuates and weird electrical problems

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tookien

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I have a weird issue happening, I noticed it happens only during and after rainy conditions.

First issue is:

- The speedometer needle goes up and down abruptly then stays down.

Second issue is:

- What's accompanied by this is the locking/unlocking the doors, the doors locking mechanism engages itself randomly even while driving.

- When I used the keyfob to unlock the doors it locks right away.

- Although when I use the key to manually unlock, it works.

- The doors lock also engages each time when I let go of the switch for the power windows.


These issue stay for some period of time and eventually returns to norm after a few days.

This generation rav4 2003 (awd, auto) tend to have ECU issues, related to transmission (hard) shifting issues, but I had that repaired already.
I have another repaired ECU as well that has had this same problem.

All this leads to conclude some electrical wiring issue/short somewhere, or indeed the problem is still at the ECU.
I checked the fuses no fuses are blown.
I already had all ground points cleaned up.
And checked for any water getting in to connectors but couldn't find anything.

Any suggestions?
 
I guess it is a problem with the alternator, if these problems occur with engine running. Check volts out of alternator (alt) to ground, should be 13 to 14 volts. Next using a multimeter, set to millivolts AC. Check the same way alt. output to ground. This checks for ripple current. It should be less than 50mv. Ripple occurs from failing capacitors in the alt.
 
Last edited:
Originally Posted by irad
I guess it is a problem with the alternator, if these problems occur with engine running. Check volts out of alternator (alt) to ground, should be 13 to 14 volts. Next using a multimeter, set to millivolts AC. Check the same way alt. output to ground. This checks for ripple current. It should be less than 50mv. Ripple occurs from failing capacitors in the alt.


Thanks. Problem occurs whether engine running or not.
 
Originally Posted by Dinoburner
Grounds grounds grounds.


Yep. And if not that test your charging system (alternator, battery) including a resting test and load test of your battery.
 
Originally Posted by Dinoburner
Grounds grounds grounds.



Thanks.

I suspected the grounds before so I removed and cleaned up the ground to the negative terminal on the battery. The battery is also new.
Also removed and cleaned up all the other ground points in the engine bay.

Are there really other ground points to consider maybe under the vehicle or interior?

I assume it's gotta be a ground point at some main connection module since there are multiple problems.

Under the dash the connections all seem very clean, no rust or corrosion.
 
Originally Posted by Dinoburner
Perhaps there is a copy of vehicle wiring schematics on line that will show ground points



Thanks. I found a schematic online.

There are 4 more ground points in the interior front. Two around the kick panels at both sides where corrosion could set in. I don't see how as I've opened it up before, but I guess it's worth checking.
 
Originally Posted by tookien
Originally Posted by Dinoburner
Grounds grounds grounds.



Thanks.

I suspected the grounds before so I removed and cleaned up the ground to the negative terminal on the battery. The battery is also new.
Also removed and cleaned up all the other ground points in the engine bay.

Are there really other ground points to consider maybe under the vehicle or interior?

I assume it's gotta be a ground point at some main connection module since there are multiple problems.

Under the dash the connections all seem very clean, no rust or corrosion.


Had similar issues in my 2006 Corolla. Definitely "Ground" related.
I searched out all possible Ground connections inside the Engine bay.
Cleaned, sanded and then coated them with Lithium grease.
If your RAV4 is anything like my Corolla, there's a hidden ground connection to the chassis under the Battery tray.
Remove Battery, then the tray (two 10mm bolts) and you'll see it plain as day. It's a big one.
That solved my issue....Good Luck!
thumbsup2.gif
 
Originally Posted by incognito_2u
Originally Posted by tookien
Originally Posted by Dinoburner
Grounds grounds grounds.



Thanks.

I suspected the grounds before so I removed and cleaned up the ground to the negative terminal on the battery. The battery is also new.
Also removed and cleaned up all the other ground points in the engine bay.

Are there really other ground points to consider maybe under the vehicle or interior?

I assume it's gotta be a ground point at some main connection module since there are multiple problems.

Under the dash the connections all seem very clean, no rust or corrosion.


Had similar issues in my 2006 Corolla. Definitely "Ground" related.
I searched out all possible Ground connections inside the Engine bay.
Cleaned, sanded and then coated them with Lithium grease.
If your RAV4 is anything like my Corolla, there's a hidden ground connection to the chassis under the Battery tray.
Remove Battery, then the tray (two 10mm bolts) and you'll see it plain as day. It's a big one.
That solved my issue....Good Luck!
thumbsup2.gif




Thanks. I'll check that out.

I checked the schematics they don't seem to show any ground connection under the battery tray...
 
Originally Posted by irad
I guess it is a problem with the alternator, if these problems occur with engine running. Check volts out of alternator (alt) to ground, should be 13 to 14 volts. Next using a multimeter, set to millivolts AC. Check the same way alt. output to ground. This checks for ripple current. It should be less than 50mv. Ripple occurs from failing capacitors in the alt.


Alternators have diodes . Did not know they had capacitors ?
 
Originally Posted by tookien
Originally Posted by Dinoburner
Grounds grounds grounds.



Thanks.

I suspected the grounds before so I removed and cleaned up the ground to the negative terminal on the battery. The battery is also new.
Also removed and cleaned up all the other ground points in the engine bay.

Are there really other ground points to consider maybe under the vehicle or interior?

I assume it's gotta be a ground point at some main connection module since there are multiple problems.

Under the dash the connections all seem very clean, no rust or corrosion.


If you take a set of jumper cables & use only 1 leas & go from the negative / ground , on the battery , to the engine block , see if that changes anything .

Take the other lead and try to go from battery negative to a good body ground . Any change ?

Both with engine off and engine running ?
 
Originally Posted by WyrTwister
Originally Posted by tookien
Originally Posted by Dinoburner
Grounds grounds grounds.



Thanks.

I suspected the grounds before so I removed and cleaned up the ground to the negative terminal on the battery. The battery is also new.
Also removed and cleaned up all the other ground points in the engine bay.

Are there really other ground points to consider maybe under the vehicle or interior?

I assume it's gotta be a ground point at some main connection module since there are multiple problems.

Under the dash the connections all seem very clean, no rust or corrosion.


If you take a set of jumper cables & use only 1 leas & go from the negative / ground , on the battery , to the engine block , see if that changes anything .

Take the other lead and try to go from battery negative to a good body ground . Any change ?

Both with engine off and engine running ?



Thanks.

I can't even test it now because it's back to normal now this morning.

I'll clean up the rest of the grounds and hopefully the issue doesn't come back when it starts raining.
 
failing can/man data connections can do this too. Failing Body Computers in Chryslers do this as well. Is the ECU or BCM or any other controller getting wet in a way that could get into the the connector?

There will be a massive pass-through at the firewall? Is its seal compromised?
 
Originally Posted by irad
I guess it is a problem with the alternator, if these problems occur with engine running. Check volts out of alternator (alt) to ground, should be 13 to 14 volts. Next using a multimeter, set to millivolts AC. Check the same way alt. output to ground. This checks for ripple current. It should be less than 50mv. Ripple occurs from failing capacitors in the alt.


AC ripple occurs because of failing/failed diodes in the alternator, not capacitors
 
Originally Posted by meep
failing can/man data connections can do this too. Failing Body Computers in Chryslers do this as well. Is the ECU or BCM or any other controller getting wet in a way that could get into the the connector?

There will be a massive pass-through at the firewall? Is its seal compromised?



The ECU is definitely in a good place.

But there is a plastic cover that covers the battery and also seal water from coming through as it covers the front windshield.
This is just installed with plastic holders/caps. It's like that by design, but it did cross my mind whether water could get through there but the seal isn't really tight.

All the places I checked so far no water coming through, all seals at firewall look good.

I noticed today that the ground cable going from the engine to chasis has a junction/connection.
I disconnected it and looked pretty dirty. Not sure if that could be the problem. The cable is thin and seems a little corroded.
I cleaned it up . I have a new thicker gauge ground cable but not sure if this would even cause the problem.
 
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