To all the people with Sierras running a G16B engine who havent got around to hooking up the check engine light, im going to show you a way to check for codes without having a check engine light.
What you'll need:
Some speaker wire
Tape
Pliers
Small dash light globe (in black circle)
(dont use too big of a globe or you might fry what drives the light in the ECU, go out and buy a dash light globe or just steal the one from behind the heater control)
Pull the wire tabs on the back of the globe out straight then strip the end of the speaker wire around the tabs, you could solder it if you wanted but there is no real need.
Once you have done that put abit of tape around each wire so they cant short out on each other.
Strip the other ends of the speaker wire and test the globe across your battery terminals to check that it works.
Hook one end of the speaker wire to a +ve, you could just put it on the battery terminal or in behind a fuse like i did (coil fuse is a good one to use)
Next you have to find the Diagnostic plug, depending on how the loom was done it could be inside the car or under the bonnet. It looks like this:
With the blank plug on the upper left you want to push one end of the speaker wire into the top right (C) plug hole, its has the purple wire with yellow stripe
Now if you have hooked the +ve behind the coil fuse the light should be out. The the engine and the light will come on for a few seconds then go out.
If you have a fault the light will stay on.
You can then check codes by putting a link in between terminals B and D on the Diagnostic plug.
For more info on checking codes see Check Engine Light Explained
Hope that works, Josh
