Electrical Headache
Thread Starter
Racer
Joined: Jul 2012
Posts: 262
Likes: 12
From: South Lyon, MI
Electrical Headache
On the starter for an 85 there are two wires that bolt onto the big stud. The one is the main from the battery, the other is three, a red, blue, and tan, grouped onto one. What are these three wires? My father and I are measuring a solid short when the main lead and these touch... This is a Doug Nash coupe. Any help is appreciated.
Heel & Toe
Joined: Aug 2012
Posts: 21
Likes: 0
Don't know if this will help any, but the Haynes manual is not showing any of those colors to the starter...I had an 85 Z28 that had something similar, they ended up running back to the alternator, but may be a little difficult to see when they go back into the loom at the back side of the engine. Your short may be in there if the wire casing has rubbed through to the block. Could also be a bypass to the starter interrupt relay...
Last edited by he_mech_usmc; Dec 19, 2012 at 11:55 PM. Reason: duh...mixed the battery and starter
Instructor
Joined: Sep 2012
Posts: 167
Likes: 0
From: Johnstown Penna
On the starter for an 85 there are two wires that bolt onto the big stud. The one is the main from the battery, the other is three, a red, blue, and tan, grouped onto one. What are these three wires? My father and I are measuring a solid short when the main lead and these touch... This is a Doug Nash coupe. Any help is appreciated.
Thread Starter
Racer
Joined: Jul 2012
Posts: 262
Likes: 12
From: South Lyon, MI
Thank you both. I'm going to be doing more troubleshooting today. I did swap engines over the summer so it's possible something got rubbed wrong or pinched. My dad and I are kinda just at a lost. we're pretty sure we've located the wires the short is on, just not the source yet...
Racer
Joined: Oct 2012
Posts: 350
Likes: 2
From: Huntsville AL
Those sound like fuseable links. Typically one goes back to the alternator output, one goes to a fuse box and one goes to the headlight circuit. You really need a manual with wiring diagrams. Have you tried the public library reference department? If you are lucky they will have Mitchell manuals which for the most part are reprints or data lifted from factory service manuals. The Haynes and Chilton's manuals are hit or miss when it comes to wiring information.
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Just buy a set of FSM?
haynes and childrens manuals are useless. Unless you have a wobbly table.
The elec book in the FSM is nothing but electrical drawings for that specific year. Too much necessary info on a car thats wayyyyyyyyy to complex to wing it. Whats $75 when you;re lost?
Gotta remember this is NOT the typical Chevy/Gm system. It has some variant of the Theft Deterrent system, or Vehical Anti Theft, and it may interface with the ECM and/or distributer at some point. 85 was pre-VATS, so you really need the FSM for this. The color codes in the FSM are absolutely fool proof and the drawings easy to follow with great detail.
My 87 FSM only shows purple from the key switch besides the battery cable, but thats after going thru a bunch of other things, like vats, clutch, trans and other safety devices. Yours being earlier may have some of those things arranged in a different route. If you have an aftermarket alarm then one wire is there to the alarm for interrupt or alarm activation if its not getting the corrosponding signal via the ignition switch.
haynes and childrens manuals are useless. Unless you have a wobbly table.
The elec book in the FSM is nothing but electrical drawings for that specific year. Too much necessary info on a car thats wayyyyyyyyy to complex to wing it. Whats $75 when you;re lost?
Gotta remember this is NOT the typical Chevy/Gm system. It has some variant of the Theft Deterrent system, or Vehical Anti Theft, and it may interface with the ECM and/or distributer at some point. 85 was pre-VATS, so you really need the FSM for this. The color codes in the FSM are absolutely fool proof and the drawings easy to follow with great detail.
My 87 FSM only shows purple from the key switch besides the battery cable, but thats after going thru a bunch of other things, like vats, clutch, trans and other safety devices. Yours being earlier may have some of those things arranged in a different route. If you have an aftermarket alarm then one wire is there to the alarm for interrupt or alarm activation if its not getting the corrosponding signal via the ignition switch.
Race Director
Joined: Aug 2007
Posts: 11,889
Likes: 8
From: Whitefish Falls Ontario
St. Jude Donor '08-'09
Not sure how similar the 85 is to the 84, but I have three fusible links with the main battery wire. One brown to the main alt. post plus two red. One goes to the alt. regulator and the fuse panel and the other to the fuse panel also.
Hope this helps..
Hope this helps..
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Drifting
Joined: Jun 2009
Posts: 1,284
Likes: 443
From: Upstate NY
I had the same thing happen on my 84 4+3. Turns out when I replaced the starter I had the hot lead attachment turned upwards on the stud -just enough so that it was hitting the dip stick tube ...actually ended up arcing and welded spot welded the dip stick in...LOL
Race Director
Joined: Aug 2007
Posts: 11,889
Likes: 8
From: Whitefish Falls Ontario
St. Jude Donor '08-'09
Thread Starter
Racer
Joined: Jul 2012
Posts: 262
Likes: 12
From: South Lyon, MI
The meter I have allows one to switch the polarity of the leads. When we switch the polarity, it'll go from the 35-40 ohms to even less resistance... 
Switch it back, and back to 35-40...
Switch it back, and back to 35-40...
Thread Starter
Racer
Joined: Jul 2012
Posts: 262
Likes: 12
From: South Lyon, MI
I know I need a FSM, i'm working on that. Currently I took all the leads off of the starter. With an OHM meter, the positive clip on the battery lead, negative on ground (exhaust), no short. Positive lead on the small lead from the ignition to ground, there's a short. The same short occurs on the three into one to ground. This is where I'm at, any two cents appreciated.
Thread Starter
Racer
Joined: Jul 2012
Posts: 262
Likes: 12
From: South Lyon, MI
And after unplugging the main harness from the drivers side, the short disappears... I'm just thinking out loud but I think i'm tracing this problem to the ignition swith? Or something in the steering column...
Race Director
Joined: Aug 2007
Posts: 11,889
Likes: 8
From: Whitefish Falls Ontario
St. Jude Donor '08-'09
The largest of the three (IIRC 10 awg) should go to the main post of the alternator, plus one of the others ( 12 awg) to the voltage regulator in the alternator. Try disconnecting these at the alternator and see what you get..
Last edited by ccrazor; Dec 22, 2012 at 05:01 PM.
Thread Starter
Racer
Joined: Jul 2012
Posts: 262
Likes: 12
From: South Lyon, MI
Yea, I tried unplugging the alternator. A short still exists. What I've found is when I unhook the main harness from the firewall by the battery, the short disappears. when i go to hook it back up, its the lower portion of the connector where the short is. I'm currently tracing those wires. I know I'm getting closer slowly, haha
Thread Starter
Racer
Joined: Jul 2012
Posts: 262
Likes: 12
From: South Lyon, MI
Yes! Here's where I'm at. Pulling the CSTY/CLK fuse gets rid of our solid short. Hooray! But, I currently can't get the car to crank over. I want to get it running without that fuse, then I can work on tracing it... If I jump the starter with a screw driver it cranks, when I turn on the key, the dash lights up and i can hear the fuel pump. When I hit the key, it doesn't crank... So now I'm chasing through everything in the starting system...
Race Director
Joined: Aug 2007
Posts: 11,889
Likes: 8
From: Whitefish Falls Ontario
St. Jude Donor '08-'09
On an 84 power goes from the ignition switch to the clutch start switch, to a starter interrupt relay (controlled by the theft deterrent module) through n/c contacts to the solenoid.. For the fuse check the lighter, been known to be a problem..
Last edited by ccrazor; Dec 23, 2012 at 04:20 PM.
Thread Starter
Racer
Joined: Jul 2012
Posts: 262
Likes: 12
From: South Lyon, MI
Gotcha, I found some things talking about jumping the starter interrupt relay, I'm gonna see if I can hunt this down. Thanks for bearing with me. I'm just thinking out loud... I see that the CTSY/CLK fuse could be related to my starting issues though...
