Jump to content
The mkiv Supra Owners Club

How To: Check the diagnostics codes

Ian C

Recommended Posts

When things go wrong with engine components, sensors, etc. there is a chance that it's going to be a failure mode that your ECU will recognise. Usually, you'll know something has happened because the MIL (Malfunction Indicator Light, the red exclamation mark) lights up.


The ECU stores an error code so that you can check later what the problem is/was. Rather than requiring a bug diagnostics machine, you can use a simple paperclip, or a short loop of wire. You use this to bridge the connections E1 and TE1 in the diagnostics port ( Location, 4th thumbnail along )


For VVTi use Tc and E1 (from this thread)


Update - Make sure you have de-immobilised your car! Some immobilisers stop the engine light from flashing.


This makes the ECU flash the orange check engine light (not the red MIL light) when the ignition is switched to position 2. If it's a regular flash then there are no stored codes. Otherwise it will blink a few times, pause, blink a few times, and then give a longer pause. That's one stored code, and the number of blinks is the digit, so:

blinkblinkblink pause blink pauuuuuse


Is code 31. You may have more than one stored code, so it'll work its way through them from lowest to highest. It will then loop back to the start again.


For example, if you had a misfire and you also had a problem with your speed delimiter you may find you got:


blink pause blinkblinkblinkblink pauuuuuse blinkblinkblinkblink pause blinkblink pauuuuuse repeat


Which is code 14 (problem in ignition circuit) and code 42 (No1 speed sensor problem)


These codes are stored indefinitely and only cleared when you reset the ECU in some way (fuse removal, battery disconnect/flatten). This means you may have some red herring codes stored if you are at the initial stages of diagnosing a problem, so resetting the ECU, triggering the problem, and then reading the codes is the best method.



ECU Diagnostic codes 1.jpg

ECU Diagnostic codes 2.jpg

ECU Diagnostic codes 3.jpg

ECU Diagnostic codes 4.jpg

ECU Diagnostic codes 5.jpg

Edited by Pete
Misleading warning light description (see edit history)
Link to comment
Share on other sites

  • 1 year later...

:welcome: mate, sorry to hear you got probs already.:(


If I am reading the manual correctly, fault code 42 is No.1 speed sensor. 2JZ-GE engine


All conditions below are detected continuosly for 8 sec or more.

(a) No. 1 speed signal: 0 km/h (mph)

(b) Engine speed : Between 2,000 rpm and 4,500 rpm

© Coolant temp : 80° C or more

(d) Load driving


Trouble area.

No.1 speed sensor

combination meter

open or short circuit in No. 1 speed sensor circuit


Link to comment
Share on other sites

  • 8 months later...



I may have completely lost the plot here but shorting TE1 and E1 doesn't seem to work for me! I have an L Reg UK spec mkIV. When I short them and then turn the key to position 2 I get a couple of seconds of interesting clunking noises from the engine bay and then two constant flashing indicators, the "over drive off" one and the orange engine warning light at the left of the right hand bank of warning indicator lights.

I was expecting the MIL (big red exclamation mark in the centre) to at least flash constantly and more likely give me a bunch of codes. It remained completely constant with no flashing at all...


I'm quite sure I connected up the right terminals as they are marked on the label in the diagnostic port cover.


Any ideas as to what I've done wrong?




Link to comment
Share on other sites

It's the orange engine one that you should be looking at.
It is, but that's not what it says above.

I've noticed a few people being confused by this. I think the first post should be corrected where it says "this makes the ECU flash the MIL when the ignition is switched to position 2"

Link to comment
Share on other sites

  • 9 months later...
  • 4 months later...
  • 11 months later...
  • 9 months later...
  • 1 year later...
  • 1 month later...
  • 3 months later...
  • 3 months later...
  • 1 month later...

Guys, I have a VVTi engine. Trying to figure out why my DBW is not working. Did connect the Tc and E1, but check engine light is not blinking. The only thing blinking is the airbag light. Blinking constantly. I have de-immobilised the car as suggested in the first post. But check engine is still lit permanently and does not go out when the engine starts. Any ideas what am I doing wrong? Or maybe just the problem is not common, so no error code is recorded?

Link to comment
Share on other sites

  • 2 months later...
  • 3 weeks later...
  • 2 months later...

Hey guys sorry to revive an old thread but I have a problem with my supra.


The MIL light stays on all the time. When i short the two pins on the dlc2 (tower brace blocks access to dlc1) the slip count and abs lights flash repeatedly.. I have read that it should be the check engine light and the overdrive that should flash? can anyone point me in the right direction?





Link to comment
Share on other sites

  • 4 weeks later...

I have a 2000 JDM RZ, recently the car died on me at random at low kms (sub 10km/hr) and wouldn't start for a good 20minutes (apparently could be coil packs??)


Car has travelled 54,xxxkms (genuine) - and I tried running diagnostics.


Diagnostic port under the dash (circular one, found out later it is disconnected LOL) bridged TC & E1 - my indicators flashed 15 times, nothing else, weird though seeing that port isn't connected??


Or maybe that meant code 78?


OBDII connecter under the dash - haven't tried anything as don't have a diagram and ports aren't labelled.


Diagnostic port in the engine bay - can't bridge TE1 & E1 (TE1 has no pin) so bridged TC & E1 (these have pins, and now reading this thread makes sense seeing it is VVT-i) - my "snow" flashed on the dash, and my "abs" light flashed. No other lights flashed. At random though sometimes the airbag light flashed.


Maybe I accidently reset the ECU as initially I checked all the fuses thinking it was a fuse that was the problem hence no flashes? But why all the other random flashes?


Spent a good few hours on it last night and annoying a guru with my questions and still couldn't figure it out. :(

Edited by shifted (see edit history)
Link to comment
Share on other sites

  • 5 months later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.