Smoking coming from body/instrument ECU!! (1 Viewer)

[davespider]

Today I parked my '01 LX470...and noticed smoking coming from the front end of the passenger side running board (I keep the running boards because my elderly father in law needs them to get in the vehicle). Definitely a rubber/plastic burning smell. I didn't see any fire...so I decided to try driving the 5 miles home. I figured it was just those courtesy lights.
Well...after driving about 1/2 a mile...I noticed smoking coming from the dash right above the radio (non-nav). I proceeded to pull over at the next parking lot.
After pulling radio, I could see that there was a hole burned thru the plastic housing of the ecu.
So...I'm guessing that I need just need to replace/repair the ecu and do something about the damn courtesy lights that have never worked very well any way.
Do you think that that's all there is to it? Anything else I should look out for? I haven't pulled the ecu yet...but will tomorrow.
Thanks for all your sage advice...

 

[joshAUST]

Hi.
Doesn't look good.
Sounds like the unit has some internal short or something causing the heat generation, which could be a mosfet or similar.
Just guessing however.
You may be up for a new unit, but if you can find someone with electronics experience, they may be able to repair it.
I guess it will depend on how much they cost as to whether it will be worth it.


It could be worth removing the covers, reconnecting it briefly and seeing which component is getting hot, although it would be safer to do this with a variable power supply with current limiting, to avoid the possibility of any further damage.

Applying a low voltage, checking the temps, either by hand, or using isopropyl alcohol and seeing where it evaporates first, may help you isolate the component that is overheating...
From there, it could be as simple as replacing that component, although it could be caused by some other component that is shorted further past that component too however.

Looking at the part number on it - 82791-60031, you can get a s/hand one from ebay for around $100USD inc shipping, eg:

1998-2002 Lexus Lx470 Controller Junction Instrument Module Computer 82791-60031 for sale online | eBay

Find many great new & used options and get the best deals for 1998-2002 Lexus Lx470 Controller Junction Instrument Module Computer 82791-60031 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Hope this info helps.

Good luck

 

[davespider]

Thanks Josh...pretty much what I was thinking.

Question...would/could a short in the courtesy wiring in the running boards easily cause the ecu to burn out? I would think a fuse would burn out before the ecu fried.
I wouldn't think it could be the other way around (ecu causing the lighting to fry).

 

[joshAUST]

Its hard to say.
If you can find the pinouts for the connectors for the courtesy wiring, you could probably remove/disconnect just those wires from the wiring loom plug.
I assume they should be in the Electrical Wiring Diagram, which is part of the FSM, if you have that?

 

[joshAUST]

I'm assuming that that part is the body ECU? - although they seem to have a variety of names...
Assuming so, and going from the 2004 FSM for the 100 series UZJ100 - which should be essentially the same as a LX470, there are three connector plugs going into it, B7 (A), B8 (B) & B9 (C)

Going from the overall electrical diagram in the EWD in the FSM, the courtesy lights are located as:
Pin
B21 (Grey-Yellow) Door Courtesy light Rear LH
B22 (Grey-Red) Door Courtesy light Rear RH
A25 (Grey-Blue) Door Courtesy light Front RH
A26 (Grey-White) Door Courtesy light Front LH

I.e. B21 is pin 21 on the B8 plug, A25 is pin 25 on plug B7.

As you say, it may not be related, but shouldn't take to long to disconnect the wire from the plug to test it.
Hope this helps.

 

[davespider]

I was just checking to see if had the wiring diagrams. Apparently...it's one pdf I don't have in my folders.

So...can I just disconnect connectors B7 and B8...and will I be able to drive the car back to my house so that I can do the full repair? There's doesn't seem to be any major stuff connected to those connectors (although it is kinda hard to see what all is exactly hooked up to that ECU).
Thanks...

 

[joshAUST]

Just PM'd you.
I'd give it a shot... or at least try without A and B plugs removed.
I think the headlights may not work however, and probably tail lights, interior lights, power windows etc.
It MAY not work however, as the immobilizer MAY run through it.

Otherwise, in the EWD, there are notes on removing wires from the plugs, without damaging them.
So it shouldn't be too hard to disconnect the plugs in question, remove the appropriate wires, and then replug them.

 

[davespider]

One toasted ecu.

Problem is the one plug is partially fused into its socket. Hopefully I can dissect it out.

 

[joshAUST]

ouch!
I think it may be better to replace the unit, if you can get one around the $100 mark second hand.
You can buy the bare plug that is melted, and carefully remove each pin and transfer it... hopefully, if its not too badly melted on the inside.
If you apply some gentle heat with a hairdryer it may soften up the plastic enough to get it out.
The centre may not be too bad, as the pin sockets should hopefully have kept the plastic in the middle from warping too much, and if so, it may just plug in to a replacement ECU...although you may need to file any warped edges to fit.

 

[mfaisaln]

I need the wiring diagram so you have it?

I was just checking to see if had the wiring diagrams. Apparently...it's one pdf I don't have in my folders.

So...can I just disconnect connectors B7 and B8...and will I be able to drive the car back to my house so that I can do the full repair? There's doesn't seem to be any major stuff connected to those connectors (although it is kinda hard to see what all is exactly hooked up to that ECU).
Thanks..

 

[mfaisaln]

Just PM'd you.
I'd give it a shot... or at least try without A and B plugs removed.
I think the headlights may not work however, and probably tail lights, interior lights, power windows etc.
It MAY not work however, as the immobilizer MAY run through it.

Otherwise, in the EWD, there are notes on removing wires from the plugs, without damaging them.
So it shouldn't be too hard to disconnect the plugs in question, remove the appropriate wires, and then replug them.

Do you have the wiring diagram ?

 

[saucebox]

Do you have the wiring diagram ?

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Landcruiser 100 Series Factory Workshop Manual

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