Help! Electrical problems.....and smoke!

[cubby911T]

Hi guys. Major disappointment and almost a fire (I think).

I am, or was, approaching the end of my 3.2 conversion and hit a major problem tonight. I have been following Marc's 3.2 conversion guide as closely as possible and everything seemed to be going okay. I got the 3.2 engine installed into my '77 targa over the holiday weekend and re-connected the clutch and all the electrical connections. Before proceeding with the oil lines and CV joints, I thought it might be wise to attach the battery and "bump" the starter just to see if it would engage.

That's when the initial disappointment happened.....nothing but a 'click' when I turned the key. Then, just as that was sinking in, I looked up and saw a faint waft of smoke coming from the luggage compartment just in front of the dash. "Holy ****!!" I quickly disconnected the battery and tried to locate the source of the smoke. My new DME wiring appeared to be okay, but I could see some trouble up by the back of the gauges. I pulled the oil temp/pressure gauge and the gas gauge and found this:






The brown wire (ground?) that bridges the two gauges is totally cooked. Also, you can see a little patch of a green wire in the foreground is damaged as well, but I don't know if that was due to its proximity to the brown one. What could cause this type of meltdown? The only wiring change I made to this general area was changing out the tach signal wire, but the back of the tach looks fine. I did change out both the oil pressure sender and the oil temp sender on the 3.2 so that they would be compatible with my '77's gauges. Could something be screwed up with that? Could it be related to the problem with the starter not engaging?

This has me pretty freaked out. Not only am I seriously disappointed about the starter, I am now very nervous about the wiring. Can anyone help me sort out this mess?

Thanks,

[mca]

I did the EXACT SAME THING on Saturday. Tried to hook up a temp/pressure gauge from an older SC. I turned the key and smoke came out eveywhere behind the dash.

I still don't know why the connection was wrong. Regardless, I went and got some 18 gauge wire from O'Reillys and fixed the brown and red wires.

If you can trace the wire to where the insulation burn stops, cut it there and add new wire.

I was able to complete this fix in a few hours ... working through the dash gauge holes. And I am far from being comfortable working with electrical stuff. She fired right up.

From the pics, looks like you got lucky. That brown one will be ez. That green one coming off of the tach needs to be investigated.

ps... I changed out my temp sender but not the pressure sender, I wonder if that was what caused mine to fry. Please let us know if you can determine the cause.

[cubby911T]

I just walked back out to the car and found something highly disturbing. When I pulled the gauges out to examine the charred wiring, I saw some electrical tape fall to the floor. Upon closer examination I found this little gem of engineering genius:



Yes, folks, that is a indeed a pair of alligator clips attached to a single light bulb. Un-fricking-believable. Now that I think about it, I do recall the PO of my car mentioning something about having a problem with the light bulbs in the instrument cluster. This must have been his "farm fix" for that problem. It never caused a issue before, but perhaps when I had the tach out last week to change out the tach signal wire I disturbed this rather delicate instrument. Could this be the most likely culprit for my meltdown?

[Brian 162]

Go buy a lottery ticket.

[billybek]

Score!!!
Double roach clips!!!
Get a wiring diagram and try to re wire with like colors if at all possible.
Good save pulling the power...Could have been nasty...

[Zeke]

+1 on "Un-fricking-believable." Whomever did that.... well, I'll desist.

[dshepp806]

Get your prints in order and map this bullsheait out properly.....alligator clips? Pleaze!!!!!!!!


Best,

Doyle

[cubby911T]

So is it a safe bet that the "double roach special" was causing the wiring to smolder? Is there any possibility it may have been the new senders I installed on the engine? I don't know exactly how the clips were situated, but I'd like to understand exactly what chain of events caused that brown wire to overheat. Note: I don't think there is any remapping to do, per say - - just replacing some charred wire.

Also - my starter problem. I am using the same starter and ring gear as before, which showed no signs of trouble before my engine conversion. I gave my battery a full charge 2 days ago so that should be okay. I do hear the solenoid clicking. Should I try to turn the engine a little or whack the starter with a mallet like I've read on other threads?

[mca]

Yikes. That is pretty ridiculous.

Good thing you found it and can remedy the situation.

If you have heat exhangers, make sure that you attach the heater hose on the passenger side next to the starter. I didn't do this and my starter wires ended up on my heat exchanger - burned off the insulation and made them crispy.

Like you, I just installed a new engine. Don't make the same mistake I did.

[cubby911T]

Originally Posted by mca

If you have heat exhangers, make sure that you attach the heater hose on the passenger side next to the starter. I didn't do this and my starter wires ended up on my heat exchanger - burned off the insulation and made them crispy.

MCA - yep, it's all hooked up. I replaced all the heating components while the engine was out.

thanks,

[mca]

Good luck with it. I about lost it when it happened to me. Threw up in my mouth a little.

Because of my lack of experience with wiring, I was pretty apprehensive about digging in and trying to fix it.

Hopefully you can determine why it fried. I would eventually like to backdate my gauge to the numbered version. I didn't even know that the pressure sender needed to be changed. Maybe that was the cause ... but until I know for sure I am not touching it again.

[ChkbookMechanic]

Things like this are why I dislike looking underneath my dash because I know I'll find something like this and it'll just tick me off. As others have said, it was a good thing you were able to catch it before it really got out of control. Even though I'm an electrical engineer by education and have wired up some complicated things, sifting through pages of circuit diagrams and repairing burnt wires is not my idea of fun.

[euro911sc]

Hey, did you find anything else to go with those roach clips ?

It would baffle me if this happened simply from changing a gage sender/sensor... The only reason you change sensors is to get the voltage to metric curve to match the gage so it points at the right number. It's not like you put in a 6v gage into a 12v system. They should all run off 12v... there must have been a short somewhere.

If you search for harness on here you will find a thread to a company that can provide you OEM color wires... not cheap, but if you are determined to use it there ya go. If not, Radio snack

-michael

[cubby911T]

Originally Posted by mca

Good luck with it. I about lost it when it happened to me. Threw up in my mouth a little.

mca - you just described my exact feeling at that moment! Couldn't have said it better myself. I'm really, really hoping it was the roach clips that caused this problem. I will try to rewire tonight and see what happens.

[cubby911T]

Originally Posted by euro911sc

It would baffle me if this happened simply from changing a gage sender/sensor...

Well, that's encouraging to hear. I kinda thought the same thing, but like mca I am a novice on wiring so nothing would surprise me.

[mca]

Radioshack didn't have the wires I needed. All of them were too large.

I went to Radioshack, NAPA, and Lowes ... then finally found what I needed at O'Reilly's. They had all sorts of colors. Even pink if you are so inclined .

[Ron.G]

Did you have the ground strap hooked up from tranny to chassis?
I wonder if the starter was using those tinny green and brown wires for ground .

[cubby911T]

Ron - hmmmm....that's a good question. I don't remember disconnecting any ground straps from the tranny when I dropped the 2.7 out. Does this strap tie into one of the starter posts or is it elsewhere on the tranny? And where abouts does it attach to the chassis?

[Mysterytrain]

The question remains, what were the roach clips connecting and why?

[Tigerrat]

There is a copper ground strap from the nose of the transmission to the frame and a bunch of brown ground wires up top on the left side of the engine. That's on my 88 3.2.
Also if that's just a regular 12v bulb I don't think it alone would draw the current to melt the insulation in the pics. Those clips could have touched and shorted something. Ken





there