Error Code 42....what next?

Tech Guys can you help?

Posted this thread last week http://www.mkivsupra.net/vbb/showthread.php?t=135126

and as the all knowing Ian C predicted I have a error code 42 stored.

My question is what next? I have read through the old threads and can see that there options for re-wiring, replacing the odo etc... but where do you start...what do you do first to start closing in on the problem?

I am fairly non technical on all this so am I best to give it over to someone who can solve this?

Any advice appreciated.

Pin 2 on the single plug of the ECU, a pink wire, is your vehicle speed sensor feed to the ECU. It's normal for a few things to get spliced into that so your first port of call is to uncover the ECU and check that wire for obvious dodgy wiring issues.

Otherwise it's either the wiring or the sensor itself. You'll want to find the wire from the sensor as near to it as possible and see if you can measure an output from the sensor - might need someone else driving/multimetering at this point If you verify the sensor is working, and it probably is, then it'll be the wiring somewhere. The classic places to fail are the back of the speedo (dry solder joint), wiring around a speed limit defeater/speedo convertor, the convertor/delimiter unit itself, or where things get tapped into the wire at the ECU.

There are various writeups on here regarding the back of the speedo issue and it's fixes and workarounds. Testing any SLD/convertors is simply a matter of bypassing it and seeing if the error code goes away.

That should keep you busy

-Ian

Code 42, my specialist subject.

There's some basic diagnostics you can do (like looking whether the speedo still works), but it's likely to be one of two things:

1) a previously-fitted DSC (speed converter) has given up

2) the odometer PCB has developed a fault. They're about 14 years old now, and they tend to either develop bad solder joints, or the bufering circuit tends to give up.

If your speedo reads in MPH, try removing the DSC from the car and see if the problem still occurs. To test it, you'll need to get the engine warm and reach at least 50ish mph. 60mph will be plenty.

Cheers guys, appreciate your help....looks like I have some investigating to do....

One other question. In the meantime am I OK to continue driving the car around? As I dont want to be causing any further problems?

Yes, it should be fine to drive the car when it's a code 42 error (I did). Code 42 is almost always an electrical hiccup rather than a serious fault.

Your power steering could be permanently on the lightest setting, making driving at speed a bit interesting, and your autobox if you have one may also get rather confused. And the active spoiler but meh.

-Ian