Mk4 LS400 - Code reader won't connect to car - Has anyone on here successfully connected one to a UK LS400?

[Yoda400]

Hi Chaps

I've been trying to diagnose a misfire on my 1999 LS400 and i'm getting nowhere. I really need to connect a code reader to the car, but it's just not communicating.

I thought that the caps in the ECU were knackered and that's why the reader wouldn't connect. Just had the caps changed and it's sorted out a lack of power (which I thought was related to the misfire), but the reader still won't connect. 

I've tried the reader on my Mum's Yaris and it connects perfectly.

Using the cable test, it shows errors on:

CAN-H, CAN-L, L

I have looked at the physical OBDII connector on the car and it looks fine, no damaged pins that I can see, but there are only 5 wires going to it. Should there be 7 going to it (going by the cable test)?

I'm just stumped by this and i'm wondering whether the car doesn't actually support OBDII because it's before the standard came in?

Thoughts anyone? Any input gratefully received, getting really frustrated by this now...

 

[Yoda400]

Anyone have any information or thoughts at all? 😓

[Ben01]

Short answer, as far as I know it - Toyota used standard OBD2 in theory (OBD2 came in USA 1996, and Toyota implemented OBD2 wholesale), but they modified communication protocol a bit (a timing for handshake between processors, and other details like this). And there is no any modern and popular IC for serial communication which fits this deviation. And nobody has money nor will to produce very special program/processor just for a few old toyotas and lexuses. I don't remeber exactly date, but Toyota changed mind around 2000 something, and fit the "normal" protocol. For example, I could not connect fresh WiFi OBD2 to GS 1998, same box works flawless with GS 2002. Only practical option to connect to elder toyota/lexus is to buy original toyota interface ("cable"), probably second hand and still bloody expensive.

[Ben01]

Other thought - to exclude malfunction of OBD2 port or ECU, I would ask any toyota/lexus service in the area if they could connect to this LS, and if yes try them once. Even if you have to pay, it is valid informaton about OBD2 port and about misfire. I got same story like 7 years ago with much more exotic, Pontiac with ALDL from 1994, I tried all ALDL converters and all normal opel/vauxhall/daewoo interface I could found, zero results, maybe port broken? next given up. But one day I recognised at some very fashionable and expensive "americans" garage the owner keeps an oldsmobile similar to my pontiac. I jumped in, discussed a bit, guy dug into drawer and brough ancient handheld diagnostics for all old GMs. Next he has connected immediately and brough all details from ECU like modern OBD2. I was proper shocked, with guy comments too "There is a reason this handheld cost, even now, more than this car or my oldsmobile, probably it is last one in whole country". And he was superfriendly and this check was for free.

[Yoda400]

Hi Ben,  thanks a lot for the comprehensive reply, really appreciate it! It's not what I wanted to hear but it's what I suspected, I *think* I read something similar a while back, but i'm also sure I read that some people had success connecting (think that might have been US market LS400s though!). Bleedin' cars eh! 

Now...Anyone happen to have a genuine Toyota/Lexus code reader stashed away that will read UK LS400 codes?

🙂

[Dan D]

Hi there, 

I've had the same problem talking to my '98 LS400 Mk4. My research came to the following conclusion:

On a UK LS400, the port that looks like 'ODB-II' under the dash is not in fact 'ODB-II'. It is referred to by Toyota as 'DLC3'. It is possible to interrogate the ECU using the following method from the Celsior manual (it works on my '98, anyway):

- Place car in Park, ensure A/C is off

- Short between pins 4 and 13 on the connector socket (as per picture) - you can use a paperclip

- Turn ignition switch to 'ON' (do not start the car). 'DIAG' is displayed on the LCD display below the speedo

- Press the 'Function' button on steering wheel once - display changes to 'EFI'. If there are any EFI warning codes, it will then display 'EFI NG' and any codes in sequence; otherwise 'EFI OK' is displayed.  If 'EFI --' or 'EFI E' appears then the ECU may be partially dead.

- Press the 'Function' button again - display changes to 'VSC' - this will display the codes for VSC (if any) in the same manner

You can use Google to find lists that will tell you what the fault codes mean.

I hope that helps!

Dan

 

[Ben01]

It's valid information, but as far as I remeber, over "flashcode" or DLC3 mode, you get only rudimentary information from ECU, "fat errors" only. Nothing like "missfire on cylinder no." the OP is looking for.  With proper programme and interface you get much more from same ECU in "OBD2 mode" (and you could programme or change a couple of things in you lexus), unfortunately there is no popular interface for this job on elder toyota/lexus.