Flashing Cruise Light - Speedo Failure

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Just wondering if anyone had seen this before.....
Cruise operation generally works fine.

After hitting a pothole, the cruise disabled itself & the cruise light was flashing....

Now this behaviour is different to if the brake peddle was tapped, since in that situation the cruise disables but the cruise light doesn't flash.

Anyone have any clues as to the cause?

Cheers

[winniliss Avid PP Poster! Find all posts View Profile Close winniliss]

Re: Flashing Cruise Light

I was towing my mates boat trailer on a gravel road. One of the trailer lights broke and shorted the wiring. This affected the cruise control (same problem you are having). Once the trailer was disconnected the problem went away.

So it sounds like an electrical problem somewhere...

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Re: Flashing Cruise Light

Thanks winniliss, it does seem to be some sort of electrical issue that shows itself with severe vibration...

[K & M McF Senior Member Find all posts View Profile Close K & M McF]

Re: Flashing Cruise Light

I had this happen when my Prado was new. The dealer said if the brake fluid was low and you hit a bump, the brake fluid level switch could turn off the cruise control. I topped up the fluid and the problem went away for a short time but then returned. Turns out it was a faulty cruise control (or part thereof). Worked perfectly for the almost 10 years since.

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Re: Flashing Cruise Light

I have seen the low brake fluid level cause the "handbrake" light to come on....most people don't realise it also indicates a brake problem....

It hasn't done it to me for a while now so I haven't a clue what its problem was.....

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Re: Flashing Cruise Light

Update: It seems the issue is related to the ECU not receiving the correct speed reading from the speed sensor....Today whilst on the way to town with the cruise set on 100km/h, I could feel the engine hunting which was definitely unusual especially on the relatively flat road to town.

Upon investigation, I could see the speedo varying in indicated speed by as much as +-5km/h. I have ruled out the speedo itself at fault because the cruise was trying to compensate for the changing speeds by accelerating the car & on one occasion dropping the auto out of 4th to 3rd. In addition the speedo was misbehaving without the cruise on later in town.

However the cruise didn't start flashing or disengage this time either.

So I seemed to have narrowed it down a little further, it didn't miss a beat on the way home either so it could be difficult to diagnose....apparently there is a speed sensor in the gearbox (actually 2 - one on the input shaft & one on the output shaft (the auto gearbox uses both to smooth gear changes)). The one on the output shaft should give a reading of actually speed of the car.

What I really need now is it to become quite evident so it's easily fixed.....I'll see how I go.

Cheers

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Re: Flashing Cruise Light

Hitting a pot hole could have moved one of the connectors in the speed detection circuit.

They can get covered in muck and any movement can cause a poor connection.

Try unplugging the plugs on the gear box and giving them a good clean.

Cheers

LeighW

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Re: Flashing Cruise Light

Mud...on my Prado? Ummm OK so I have driven thru mud.......(don't mention the alternator :shock: )

OK I will have a look, do you know where these plugs are or will they be obvious (...if obvious please also still supply a description of where )

Cheers

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Re: Flashing Cruise Light

Mud...on my Prado? Ummm OK so I have driven thru mud.......(don't mention the alternator :shock: )

OK I will have a look, do you know where these plugs are or will they be obvious (...if obvious please also still supply a description of where )

Cheers

There's three all together, two on the transmission and one on the tranfers case I think, depending on if skid contolls provided etc.

On the transmission, one is on the passenger side just back from the bell housing and about half way up from the bottom.
The other is on the drivers side, just back from the bell housing is a big connector, thats the park nuetral switch, then the oil
cooler unions then the speed sensor connector.

I'm not sure which is for the combination meter, maybe someone else can help further, else try searching for speed sensor
and speedo.

LeighW

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Re: Flashing Cruise Light

Thanks I'll have a look & see what I find....

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Re: Flashing Cruise Light - Speedo Failure

About a week ago the better half said that the speedo dropped to zero so we booked it into the speedometer place for today to get them to have a look. Of course on her way home it worked fine!

So today they had a look, it didn't play up of course but they have re soldered a number of suspect joints on some PCB's in the speedo area.....time will tell if this is the fix.

Cheers

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Re: Flashing Cruise Light - Speedo Failure

Well the speedo is still playing up....it was cool this morning around 8 degrees.....speedo didn't work till nearly in town (30km). Also the engine light came on which is new :shock:

Turning the car off & on fixed the engine light but not the speedo. When I get a chance I will see if I can get the code & look it up.

Booked in next week for the speedo place to have another look. They want it for a few days which I can understand since it very intermittent & it appears colder temperatures are making it worse.

Cheers

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Re: Flashing Cruise Light - Speedo Failure

Just an update incase anyone else has similar issues....

Speedo was still playing up, infact it stopped working at all at one stage & we had an engine light come on. Restarted the engine & the light went away.

Speedo mechanic investigated the wiring loom & found a possible issue when a connector was able to be undone without releasing the clip. We also got a 3rd party sender in & fitted that. It was still very intermittent so we are still not sure if this is the final resolution.

Cheers