JohnnyK

Hey guys, just finishing up teh electrical in this 5.0 to 67 swap (ANd the harness wasn't really modified, so thats not the problem) and I wanted to add a CEL to the harness. It's an 88, and to my surprise, they don't have one. I swear, I tested before and the pin 17 wire grounded itself on startup (I couldn't check if it opened again after it got running, because, it's not running). So that would mean, if it grounds itself, that my check engine light would light. I hooked everything up (Had 12v run going to it, and the other side went to the end of the self test wire (Pin17)). I thought I might have saw a flicker or two when I was turning the ignition key, but nothing substantial. So then I decided to see if it grounds itself when I turn it on.. So I jammed my multimeter to check continuity into the self test plug, and touched ground, and turned the key.. It lit up, but only because I was completing the circuit from the other end of pin 17, to the chassis (So the light got 12V, and thats why it turned on, because the end of the ground wire it's attached to, was grounded from my test. The multimeter read infinity for some reason I can't figure out, but maybe thats just because I had it set to ohms? As in, if you just looked at the multimeter, it didn't look like ti was completing a circuit, butthe light lit. I'm not a multimeter wizard). So yes, I thought it grounded itself as normal like the later cars with a CEL, and i remember it doing that, but not anymore?? This wire is soldered in near the plug..I Suppose it's POSSIBLE that it's just not making good contact at the computer, but I mean, everything else that i can check works as it should, so i find that pretty implausible (Fuel pump primes, so the computer itself is gettign power)...? electrical gurus? Thanks!

JohnnyK

Well I have continuitity from the self test plug, to the light, and then to the harness, so thats not the problem (As i said, unless it's not making contact with the computer, but I find that hard to believe). Is there something else that has to be connected before this will work? I can't think of anything off hand. The relays are all connected and working?

JohnnyK

Also now, if i connect a meter from pin 17 (WITHOUt the light connected to it) and touch ground, I get 12V?? Shouldn't it read 0 volts as it's supposed to be a ground?

Joel5.0

Johnny. if you're working with an '87-'88 SD computer........ they don't have the MIL driver, the MIL strategy/driver was implemented starting with '88 California MAF system setups.