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Ecu Removal


Musada
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Symptoms are, car just cuts off at random and won't restart for a while until it sits for about 30 mins,like something needs to cool down. Other than that, the car runs fine, no power loss, temp gauge doesn't go up. Changed plugs, MAF, fuel pump, fuel filter, igniters. Prior to this happening, I had the water pump and timing belt changed about a week before it started just cutting off. was told the ecu was bad and had to get it rebuilt/reman....there was a whole thread about it titled bad ecu, I'm just going to try and replace the ecu because nothing seems to be resolving the problem. I've replaced several parts and am tired of throwing random parts on the car that doesn't seem to fix it. Really need my car running

how do you remove the ecu from a 1990 ls 400

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If this started after the timing belt was replaced I would start by checking the crankshaft position sensor and the wiring to it, this often gets disturbed or damaged when a TB is replaced and the symptoms you have point towards this part failing as they can become temperature sensitive.

It is also easy to not correctly refit the wiring loom from the CPS and it ends up getting chafed by the timing belt or trapped in one of the covers over the belt.

It is located close to the crank pulley.

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  • 5 months later...

You asked for instructions on how to remove ECU; I am sorry no one told you how. I am also trying to find some instruction

as opposed to a lecture off in another direction.

And yes you can rebuild a circuit board. It might be merely replacing bad capacitors for example. That is reconditioned or rebuilt; semantics.

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  • 4 years later...

Getting ready to do this myself. Gonna just replace the ECU. Was told that Lexus is only car manufacture to offer one free evil to every Lexus owner. Not sure about that, but found some cheap online and not trying to solder. You know if I'll have to re key it? I'll post directions that I got to remove ECU in a minute!

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To get access to the engine ECU -- Inside the car, passenger side:

1) Remove the trim kick panel below the lower dashboard (it pops off--clipped into place; either leave in place or disconnect the wiring to the footwell light).

2) Remove the glovebox: First, disconnect the left-hand glove box door check, then using a screwdriver, press in then remove the clips inside the glovebox; pop out the airbag sensor on the LH side of the glovebox.  Carefully pry out the glovebox, leaving the glovebox door in place, slipping the airbag sensor out of the glovebox... leave that connected.

3) Unbolt the lower dash pad (five bolts w/ 10mm heads--two at top, three on the bottom). Pull it down/off.  On '93-94s, the engine ECU is attached to the back of this.  10mm socket to remove the ECU from the lower dash pad. 

Otherwise, Yamae's posts on the CL forum (see Trey's link above) will show you where the ECU is placed on the earlier cars.

Installation is the reverse, blah, blah, blah.

I've had good luck with ECU capacitor replacement kits from the usual online auction sources (there are sellers who have put together kits from Digikey/Mouser, which is the way I went) to replace capacitors in my LS' ECU last summer, which resolved running issues I had at that time.

Note that replacing capacitors does require some skill in electronics soldering and repair; don't attempt it if you don't have those skills.

Paul

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  • 5 years later...
On 3/21/2017 at 9:10 PM, LSPaul said:

To get access to the engine ECU -- Inside the car, passenger side:

1) Remove the trim kick panel below the lower dashboard (it pops off--clipped into place; either leave in place or disconnect the wiring to the footwell light).

2) Remove the glovebox: First, disconnect the left-hand glove box door check, then using a screwdriver, press in then remove the clips inside the glovebox; pop out the airbag sensor on the LH side of the glovebox.  Carefully pry out the glovebox, leaving the glovebox door in place, slipping the airbag sensor out of the glovebox... leave that connected.

3) Unbolt the lower dash pad (five bolts w/ 10mm heads--two at top, three on the bottom). Pull it down/off.  On '93-94s, the engine ECU is attached to the back of this.  10mm socket to remove the ECU from the lower dash pad. 

Otherwise, Yamae's posts on the CL forum (see Trey's link above) will show you where the ECU is placed on the earlier cars.

Installation is the reverse, blah, blah, blah.

I've had good luck with ECU capacitor replacement kits from the usual online auction sources (there are sellers who have put together kits from Digikey/Mouser, which is the way I went) to replace capacitors in my LS' ECU last summer, which resolved running issues I had at that time.

Note that replacing capacitors does require some skill in electronics soldering and repair; don't attempt it if you don't have those skills.

Paul

 

Ls400.docx

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