Mk4 LS400 - Anyone replaced the caps in the ECU?

Yoda400 · June 6, 2018

Hi Chaps

Anyone replaced the caps in their ECU? I'm wanting to have some work done on my car by a Lexus specialist/breaker/garage, but code readers won't connect to it, so it looks like the caps are playing silly beggars. I want to get the ECU sorted out so we can diagnose the work needed on it (a missfire that has been problematic solving!)

I know there was a chap on here selling a kit for earlier models a few years back, anyone made up a kit for the mk4?

Also - is the ECU easy to remove? Where is it located?

Thanks in advance chaps!

Matt1986 · June 8, 2018

There's a guy in the states that's well regarded for this job. Lscowboy. Look him up on Facebook. He quoted me £250 plus shipping. Fortunately I have a friend who is an electronics engineer so he's doing mine in the next few weeks. There's a great post here https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/656360-all-my-crazy-lexus-issues-solved-ecu-leaking-capacitor.html tells you what capacitors are required.

Yoda400 · June 8, 2018

Thanks for the info Matt! May I ask why you are getting yours done? What symptoms do you have?

Would you be so kind as to ask if your friend would be interested in a few quid to do mine also? He could do both at the same time? The ECU will be the same as yours (mk4)...

I'm not in a huge rush for it, happy for him to have the ECU for a couple of weeks...

Matt1986 · June 8, 2018

Hey yoda400. I've got occasional low idle, no communication from obd port, slightly off gearchanges and had a issue when it was very cold with it going into limp mode with vsc fault. Mostly it's the uncommunicative obd that points to the ECU as well as the age of the car now anyway.

It's actually a friend of mines dad who's doing the job for me. I'll ask if he'd be open to the idea but he's doing me a favour really.

Yoda400 · June 8, 2018

I bet the state of our ECUs are very similar! Along with the no communication, the VSC light flashes sometimes when setting off, performance is a bit down too. Maybe that's an ABS sensor/ring, but i'd like to get the caps sorted first so I can get some proper codes from the car. Mine also has a missfire which has stumped me, nothing has solved it and it's really spoiling the car now.

If you could ask, i'd appreciate it! Would be happy to pay a decent price to make it worth his while, plus it's doing two exactly the same - so hopefully not too much of a ballache :)

Slobbo · June 20, 2018

Clark Electronics

63 John Player Building
Stirling Enterprise Park
Stirling
Stirlingshire
FK7 7RP
Scotland

These chaps did the ones on my 95 for about £30. I removed it and dropped it off with the instructions and part numbers. They did the rest.

Yoda400 · June 20, 2018

Fab great info - thank you. So did you provide all the new caps?

What were your symptoms, and did they all disappear?

Cheers

Yoda

Slobbo · June 21, 2018

They will source what’s needed. I thought I had the erratic rpm’s but turns out I just had the air conditioner on. The car is so quiet that I would pull up at the traffic lights with the air conditioner on and the clutch would engage and rpms go up then would disengage and rpms go down. You wouldn’t normally notice it on a less refined car but the LS is so silent you do.

Yoda400 · June 21, 2018

So you had no symptoms, more of a preventative measure? Haha yes you do notice small things in such a refined car, they are wonderful machines 🙂

Thanks for the advice, i'll get in touch with them

Yoda400 · June 26, 2018

Right, I've ordered the proper caps from the US for my mk4! I've ordered a few repeats and some caps for earlier models too, so if anyone needs a Kit for theirs just give me a nudge, hopefully that can help someone out. No one here I asked had a spare kit 😞

I ordered them just so I have peace of mind the right caps have been used on my ECU, i'd be paranoid that whoever repairs it might use something different otherwise!

Yoda400 · June 27, 2018

On 6/20/2018 at 9:00 PM, Slobbo said:

Clark Electronics

63 John Player Building
Stirling Enterprise Park
Stirling
Stirlingshire
FK7 7RP
Scotland

These chaps did the ones on my 95 for about £30. I removed it and dropped it off with the instructions and part numbers. They did the rest.

Hey Rob, was it definitely these guys? I contacted them, but they quoted me between £85 and £125. I mentioned you had yours done for around £30 and the chap told me he wasn't sure about that because their min charge is £35, and the caps can be quite difficult to remove...

I said i'd supply the caps needed on mine, and mine will need 11 of them replacing. Think your's will have been 6 caps, so a bit more work, but seems to be triple/quadruple the price so I thought there must be a misunderstanding here!

Slobbo · June 28, 2018

Yes. I only had a few caps to replace and if I remember correctly I was quoted £80 or more but it was an easy job and took them less than an hour and the caps were pennies. I just checked and looks like I didn't record the cost in my log (I keep a log - yeah I'm a geek) so I can't tell you exactly how much it was but it wasn't expensive.

Yoda400 · July 7, 2018

Right, had my caps replaced on my Mk4 and it's restored a heap of power! The chap who swapped the caps for me said that there were no leaking caps/visible damage, but that wasn't to say that some hadn't gone open circuit.

The whole purpose of this exercise was so I could connect a code reader to the car to diagnose a missfire, however it still won't bloody connect. Tried it on my mum's Yaris and it connects perfectly so I figured it must be a dodgy OBD connector. I looked at it and it looks fine though?! Seriously getting peeved with the car now!

runsgrateasanut · July 25, 2018

Can I ask for the details of who changed your Caps? I'm torn at the moment between doing them myself or sending the unit and replacement Caps to someone who will do it for me? pm me if you prefer not to make it public on the forum. Thanks

ps Always assuming the Car passes its MOT on Friday.

Stupot · January 9, 2019

Resurrecting this thread as I've just replaced the ECU caps on my Mk4 1998 LS400. ECU was a pain to remove. Found a fantastic local PCM repair chap who soldered them in for me for £40. Re-install was pretty straight forward. I followed the advice to turn the key to 'run' but not start to let the ECU acclimatise for a minute or so (lots of whirring noise, VSC check light came on, then off etc) Fired up great, to huge relief. This was all done in a day, removal, repair, re-install. But I was lucky the repair chap was down the road and did it straight away.

First thing I noticed on driving, I did not need to ease the accelerator pedal from standstill or near standstill to avoid the power take up 'jolt'. So tranny seems smoother from start. More low end power accelerating off the slip road. I did have a rough idle when gear in drive but at stop for first 10-15 mins (after warm up but before fully hot). This happened for my first two short drives. So I took the car for an hours run on the dual carriageway and now the ECU seems to have learnt and that problem no longer exists. So... all good.

Hopefully in time I will discover if it's cured the random engine limp mode problem that I experienced twice in the last two months. That problem was cured by pulling over, stopping car and re-starting when it then ran as if nothing had happened... fault code read O2 sensor which can apparently be a ECU cap warning sign.

MHT · February 28, 2020

On 7/7/2018 at 9:26 AM, Yoda400 said:

Right, had my caps replaced on my Mk4 and it's restored a heap of power! The chap who swapped the caps for me said that there were no leaking caps/visible damage, but that wasn't to say that some hadn't gone open circuit.

The whole purpose of this exercise was so I could connect a code reader to the car to diagnose a missfire, however it still won't bloody connect. Tried it on my mum's Yaris and it connects perfectly so I figured it must be a dodgy OBD connector. I looked at it and it looks fine though?! Seriously getting peeved with the car now!

@Yoda400 did you use Clark Electronics for the replacement?