Just call me Sean

iTrader: (1)

If you don't know, '87's don't have a check engine light. It's there, but wasn't used by the factory until later years. I wanted to hook it up so I could read codes without hooking up a voltmeter, and hopefully the light would turn on when a problem was recorded. So I finally hooked it up today. I went through my wire collection, leftover from a GM carbureted to fuel injected engine swap, and pulled a connector that I could modify to fit into the dash plug.


I modified the connector and put it in the plug, plugged in the cluster and grounded the wire to see if the light would come on. It did, so I reassembled the dash. I then ran the wire through the firewall, crimped a connector on it and plugged it into the diagnostic port.


This is where the voltmeter negative hooks up to check for codes. The indicator lights all have power and receive ground when they need to light up. I turned on the key and the light came on, as it's supposed to.


I started the truck and then the light went out as it's supposed to. I know it will work to check codes, but I still need to test to see if it will come on when a problem is detected. The computer for this year may not be programmed that way, I'm not sure. I'll pull the MAP vacuum later to see if the light comes on, but I didn't feel like doing it right now.

aliens8mycow

Wow... it looks like the spaghetti dinner exploded!

And I thought you were too busy babysitting me to work on your own truck!

Seriously, you probably did yourself a huge favor by wiring this up - especially if the light is functional when something goes wrong.

Just call me Sean

iTrader: (1)

Well, I couldn't wait to check it so I unplugged the MAP vacuum. The light didn't come on, but I checked the codes (with the light) and didn't get a MAP code. Maybe I didn't let it run long enough to get a MAP code. I did get other codes though, but who knows how long they've been there since I don't regularly check the computer.

aliens8mycow

You'll get it - that thing will be talking like Knight Rider's car before long!

Good old Bill

Again my hat is off to you. Nice going.

andyman7931

nice work. I think I'll have to do that to my truck.

What's the difference between the 'engine' light that was already there and the check engine light? My engine light has been on ever since I put a mechanical oil pressure gauge in, should I remedy that?

Rieker

Impressive. Save some electrical tape to cover the damn thing up! lol.

ymeski56

Yank some connection that would prevent closed looping. ECT sens/switch to PCM. That aught to **** it off enough to light. I thought the "Engine" light was an 87's version of the "CEL".

Just call me Sean

iTrader: (1)

The "engine" light comes on when oil pressure drops below acceptable limits, so it really should say "oil" instead. It would be annoying to be on all the time, but the computer doesn't recieve a signal from that sensor so it's not too important to fix.

Thanks ymeski, I'll try that and see what happens.

ymeski56

This must be info in the owners manual that's usally long gone when you buy a truck used. Although nobody ever seems to read them, By the second owner they're just....gone! Like it was new assignment info on "Mission Impossible".