Wiring layout - earlier cars

Gun Doc · #1 (**permalink**) 08-02-2016, 10:45 AM

Do any of you have any knowledge of the physical layout of the wiring in earlier cars (mine is 499)? This past weekend, I fried the high amp wires on three of the power relays (horn, starter and fan). These wires are daisy-chained starting at the horn relay and are fed, I believe from the starter. I also have a dead short on all of the low amp wires going to the coil side of the relays (relays removed).

I still have voltage at the starter and the high amp side of the relays where the wires are burnt when the batt cut off is turned on. I do NOT have voltage at the input to the ignition switch…Looking at the “wiring diagram” it shows power going to the ignition from the batt cut off and spliced prior to the switch to the high amp feed on the relays. I am not sure this is accurate, or if it is, where the splice is located.

According to the diagram, the ignition switch feeds the low amp side of the relays and various fuses, but I do NOT have continuity from the low amp side back to the switch. Again, I suspect there is a splice somewhere, but short of tearing the entire harness apart, don’t know where it may be.
Bottom line is somewhere one or more splices are open and one is most likely shorted. If anyone has any idea where the specific splices are located, please share…

Thanks!

Gun Doc

spdbrake · #2 (**permalink**) 08-02-2016, 01:19 PM

Are you using this diagram?
http://www.clubcobra.com/photopost/d...ng_diagram.JPG

From what I see the "work side" of the relays power is bussed directly off the Batt Disconnect.
The three relays the control side the ground pulls the relay on the Horn and Fan, but the hot control lead goes thru the start switch, the ground waiting on the other side.

Can you circle the post(s) your seeing a ground on with the relays removed?

Gun Doc · #3 (**permalink**) 08-02-2016, 03:00 PM

spdbreak, yes I am using this diagram and you are correct the diagram does show the starter relay as going to ground off of pin 86, but the car is wired with pin 86 daisy-chained at every relay, including the starter relay to the ignition switch. I am pretty sure the drawing is backwards for that relay.

I have continuity (dead short .04 ohms) at each wire off of pin 86 at each relay (relays removed). I pulled the pins (86) out of the relay blocks prior to checking. I also checked the wiring from the start switch wire to pin 86 and have continuity.

I still have power at pin 30 of the horn relay with the batt cut off switch on, but not at the ignition switch (batt cut off side). The wires fried between the horn, starter and Fan #1 relays at pin 30 (high current). None of the wires off of the coil side (pin 86) suffered any damage on any relay.

I have looked at all the wiring I can see under the dash and haven’t found anything. It’s strange to me that there isn’t an inline fuse of some sort on the high current feed side (pin 30) of these relays between the batt cut off and relay block. I guess I’ll just have to trace both the high and low current sides back to the batt cut off and ignition switch and see if I can find a short.

spdbrake · #4 (**permalink**) 08-02-2016, 05:01 PM

The Ignition swt shouldn't have gotten smoked.

You could pull all the fuses and check for the ground again. The starter is not fused and the the 0.4 ohm could be a bad bendex.

Gun Doc · #5 (**permalink**) 08-02-2016, 05:08 PM

The ign switch didn't get smoked, but there isn't any power to it from the Batt Cut off. Switch is good - open with key off, closed with key on. I am going to isolate the starter tonight and check the readings again.

spdbrake · #6 (**permalink**) 08-02-2016, 05:33 PM

Fuse Box

Came across this thread on the BDR

Gun Doc · #7 (**permalink**) 08-02-2016, 10:10 PM

Thanks for the link.

I made some progress. First I verified that the diagram shows pin 85 and 86 reversed on the starter relay - it is wired identical to the other relays as far as switching goes. I checked the low current side where my short is and pulled each fuse, one-by-one. When I pulled the fuel pump fuse, the dead short went away and I got over 97 ohms. I don't have an electric fuel pump and the switch has never been connected. Trouble is, I can't find the green wire from the fuse to the switch. I guess I'll keep tearing into the harness. Worst case, I can always leave the fuse out.

spdbrake · #8 (**permalink**) 08-02-2016, 10:26 PM

Good info thanks.

Gun Doc · #9 (**permalink**) 05-09-2017, 11:08 AM

Ozzie, not sure if you have this diagram...

Ozzie Goat · #10 (**permalink**) 05-09-2017, 11:25 AM

thanks, I'll check it out

Quentin Z · #11 (**permalink**) 05-10-2017, 01:48 PM

My car is #272; I created this wiring diagram in my spare time a while back:

https://www.dropbox.com/s/rw3zrxszk3...agram.pdf?dl=0

BDR0572 · #12 (**permalink**) 05-11-2017, 09:04 AM

Very nice diagram, I downloaded that thanks for sharing

Sledge · #13 (**permalink**) 05-11-2017, 09:11 AM

Nice, Quentin!

BDR_Boy · #14 (**permalink**) 05-11-2017, 12:28 PM

Nice work Quentin... I too downloaded a copy... THAT should come in very handy. I do have one question for anyone. I have #509... and whereas this schematic references Ace Looms... my car is wired with a loom from Relek Manufacturing in South Africa. Are Ace & Relek one & the same? If not... and various vendors have provided wiring looms over time... what's the likelihood they all used the same colors as depicted here? Very good... good... not a chance? Just curious. Thoughts?