I am in the process of going through my new-to-me 89 Formula 350 TPI, and have found a set of 3 wires I can't easily trace, nor can I figure out what they are with the wiring diagram.

The car runs and drives fine, aside from a surging idle when cold (sticking injector? one of a 1000 things on that one). I will be getting it smogged here in the coming weeks, so am hoping whatever this is, it isn't emissions related (thanks California!). No engine lights are coming on currently.

Does anyone have any idea what the wiring may be to? .. and yes, she needs some TLC!

 

It looks like those may be coming from the wiper loom ... or coming from the distributor.

Its been a while for me with TPI, but as I recall, when I was removing the harness from my car, that the only thing in that area was the wiring to the distributor, oil pressure sender and the wipers.

My suggestion is to start with what isnt working, and start trying out the various things in the car (lights, wipers, accessories)

Is the alternator charging, is there oil pressure displayed on the gauge in the car........

 

Also get a multimeter or a test light... see if any of the wires are hot or ground and if so - at all times or igntion only.

Multimeter can be used to test continutity

 

Hard to tell from your pic. Trans lockup wiring is a possibility.

 

That's possible but IIRC, the trans lockup wires were not those colors and there are 4 of them. In the pic there are only three.
If you are confident in her Ability to run... Take her for a spin and see what your missing/not working.

 

Thanks everyone, the replies are appreciated.

After continued staring at several wiring harnesses, etc, I was also leaning towards the trans lockup wiring, since it's the only thing in that area of the harness that's that long/thin. I'm putting the car up on stands today and will get under there and trace. I'll pull out the multimeter as well and see what's up with those wires.

The funny part is everything does appear functional. Alternator is charging, gauges on the dash all functional. Wipers are also working!

I'll post up more results after I get under the car today.

 

Well, a little more than a year later, I can bring closure to this thread. Not the issue, but the wires have been identified. They are (most likely) for the oil pressure switch in 89-92s.

Pic of them in action (not my car)


I have been having cold start issues. Fires right u when warm! Went to check my fuel pressure switch and... it was missing. Should have been by the oil filter. Cross reference a bunch of photos and sure enough, the colors, location, etc all match that above.

Since this post I've gotten the engine rebuild by a shop (same block). Problem being they hid away and or cut the wires, so I do not have track of them currently. Second problem being.. no where to put this oil pressure switch.



I guess I should start a thread for ideas on this issue..

 

You should he able to get an oil pressure sending unit.
Put it in the same place if you're doing a restore or keeping it original.
IF the shop put torx or allenhead plug in there, then you will have to either remove it, or look for a place behind the distributor, just off the intake, but on the block itself, drivers side. I don't recall if there would be a tap there, but check for it. It will have a torx or allenhead plug there.

It seems since you didn't mention massive oil leaks, then that is what it sounds like to me. If either I of the plugs were out, there would be a mess of oil.

 

I will be crawling under the car again tomorrow to see if there's a plug there. I'm fairly certain they replaced the engine in the car at some stage, and didn't bother to affix that pressure switch. When I had it rebuilt they just put it back they way they found it.. sort of (can't find those former-mystery wires at the moment)

Goals at the moment are ..
1) Verify hole in block is indeed plugged off (there's a decent bit of paint in the way I'll scuff off)
2) Find the wires the rebuilders hid (or cut off)
3) Hope i can remove the plug, and reaffix pressure sensor
4) Replace connector, plug in

I have another plug I'm at a loss what it's from but that's for another day. One step at a time with this thing.

 

There's a plug there.

HAS TO BE: it's part of the mfg process of the block. It's how one of the passages that connects the oil filter, was drilled.



The plug in question is at the left side of the dwg, at the end of the passage that carries the clean oil from the center of the filter to the vertical passage drilled from the rear main cap register all the way up to the oil pressure sending unit port by the distributor.

My apologies for all the text on it; that was already there when I ganked the dwg.

 

Cheers for the informative response. I don't think I saw it due to the rebuild guys slathering a ton of paint on the block. Will clean some off as I think I can see it in my picture anyways.

Now getting it it out should be strait forward, if it works with me, just gotta find those wires again.

 

Hey brotha you mind sharing a picture of your MAF Sensor and the wiring? i cant seem to find where the wires to the MAF Sensor are located !