Annoying humming noise

[chun]

I have a 2000 landcruiser that just developed an annoying humming noise when the vehicle is powered on. Dealer told me that I need a new "Cowl-side Block junction" and another said it could be a relay going bad.

It was explained to me that when a windshield is replaced, water gets in through the screw holes and runs down to this junction block. It hums when it is going, and power windows and power locks will soon be going out.

Any thoughts?

 

[Jim_Chow]

I have a 2000 landcruiser that just developed an annoying humming noise when the vehicle is powered on. Dealer told me that I need a new "Cowl-side Block junction" and another said it could be a relay going bad.

It was explained to me that when a windshield is replaced, water gets in through the screw holes and runs down to this junction block. It hums when it is going, and power windows and power locks will soon be going out.

Any thoughts?

If they replaced the windshield correctly, there shouldn't be any leaks. IIRC, the windshield is held in by adhesive/sealant, trim mouldings, and the rivets on each side. The latter is critical to a proper installation.

 

[Romer]

Wendell, welcome to Mud.

Glad you were able to get logged on and find the 100's section.

I told Wendell his problem cause is a poor installation on his windshield. He understands that and is going to get that replaced.

The dealer told him to fix his humming problem would be a $1000 module and thats why he is here. We know how dealers are. They sell you a $300 starter instead of $25 starter contacts.

I could not find anything for him doing a search.

 

[ShottsUZJ100]

They sell you a $300 starter instead of $25 starter contacts.

LUV IT!

 

[bluecruiser]

where does the humming noise come from?

 

[NMuzj100]

Does this "humm" sound like a fax machine ? TSB for that, and a thread on the FAQ. The fix involves the combo meter.

In my experience electronics don't make noise and then slowly get worse. They usually work and then they don't. Pretty much at the speed of light.

A relay might only cost $20. And I can kind of imagine a relay making a "humm".

 

[NMuzj100]

Any thoughts?

Keep the whole truck and everyone you can influence away from this dealer.

If you get the windshield fixed right and then dry the inside by opening the windows a bit and cooking the inside on a nice dry 100 degree day. Then maybe the problem will go away.

Does this "humm" sound like a fax machine? TSB for that, and a thread on the FAQ. The fix involves the combo meter.

In my experience electronics don't make noise and then slowly get worse. They usually work and then they don't. Pretty much at the speed of light.

They are probably talking about the "Drivers Side Junction Box"
- it has 14 relays including the door lock and window relays
- a junction box has no "moving/operating parts" it is just a wiring harness/relay rack so it's unlikely to be damaged even if it got wet
- very easy to get to, just pull out the panel near the "dead pedal" at your feet
- get a piece of plastic tubing to use as a stethescope and "listen" to each relay
- A relay might only cost $20. And I can kind of imagine a relay making a "humm".
- or you could pull each one out and see when the "humm" stops

FSM page BE-14 for a diagram of the junction block.

If it's a relay, always on, then it could be the daytime running light relay. This is sitting somewhere behind the rear diff switch with a 14contact connector attached.

Another possibillity is the Reostat (dimmer switch) for the dash lights. Reostats like to "humm" so stick the tubing on it too. In fact do this first as it seems a likely source and is very easy to get to.

 

[Romer]

If you will forgive a poor 80 guy from working on a 100 series.

Wendell brought his truck over and it was making a high pitch wine. Taking stuff apart it sounded like it was coming from the silver box to the left of the gas pedal.

It comes on when there is ACC on or the engine is running. Sounded like alarm or buzzer to me.

Called Lexusben (he rocks) and he said

2000 year, yeah they had some quality control problems with metal shavings and there is a TSB

Take off the 10 mm bolt off of the 110 pin connector (looks like black module) blow both sides out with compressed air, tap and blow out again.

We did just that and fixed the problem.

No water damage and no leak that I can see. Turns out the Toyota Service Manager said it was likely water damage when he suggested the $1000 module change-out.

Wendell said he would post up, but I wanted to thank Lexusben for his off the top of his head solution to this problem. It's a common problem and may happen to your truck

 

[chun]

Problem Fixed

All,

I mis-characterized the sound. It was less of a humm and more of a high pitch sound. The problem turned out to be a problem with debris in the connector mating to the driver side junction block. This created a short that activated the alarm (high pitch sound), similar to a seat-belt not being used sound, but persistent and annoying. The solution was to remove the large connector (through the 10mm bolt), blow it out, knock any debris off the junction block, and re-assemble. This did the trick. Thre is a technical bulletin out on this very problem from Toyota.

Thanks again.