65 engine wiring harness short

[Dave K.]

Re: 65 engine wiring harness short

Rich,

Thanks a lot. Dave

[Richard M.]

Re: 65 engine wiring harness short

You're welcome, BTW, here's that wiring diagram again. Also showing the Ground connection at the Horn Relay mount bolt. It's in the horn relay harness. This is the one to be very careful when connecting. Others in the past put it on the Buss+ terminals and fried their harnesses.

The LL diagram is clearly a redo of the GM diagram which inadvertently left it out as I explained in a earlier post.

Horn1mod.jpg

[Dave K.]

Re: 65 engine wiring harness short

Rich,
I placed this ground wire lug with the horn relay ground screw that is screwed into the radiator support.

Dave

[Dave K.]

Re: 65 engine wiring harness short

Rich,Fuse 3.jpgFuse 3.jpgFuse4.jpg

Your comment was a god send. I rigged up the fuse link and checked twice. Success both times. Removed fuse and car started right up with new date coded plug wires, old 202 coil, rebuilt alternator and regulator and old hon relay.

Thanks man!Fuse 2.jpg

[Richard M.]

Re: 65 engine wiring harness short

Dave, I'm glad it worked out and you're up and running.

I'm sure you felt better about powering it up knowing the fuse was there just in case of a fault.

Good work. Only thing I'd have done is wrap those terminals with tape to prevent a problem if any movement. Maybe you did that.

Rich

[Matthew T.]

Re: 65 engine wiring harness short

---cut--

EDIT- For reference here.... Note this is a 1967 diagram but all 63-67 were wrong in this area. The error shows the 12G Black(Ground) attaching to the 12V buss bar on the horn relay. --cut--

You mention 63. Here is 63 from manual and after market color diagram. Manual no show, color yes show.

What is the reason for grounding the relay body? It should operate with no ground.

[Richard M.]

Re: 65 engine wiring harness short

You mention 63. Here is 63 from manual and after market color diagram. Manual no show, color yes show.

What is the reason for grounding the relay body? It should operate with no ground.

Matthew,

Correct, the horn relay does not need its body grounded to operate. The relay coil has constant power to one side via the Buss+, and the switching is done by grounding the other side of the coil via the horn button which switches column ground and energizes the relay, thus switching power from the Buss+ to the horns via the relay internal contacts.

The reason the wiring ground connects to the relay body is purely mechanical. It is merely a junction point to connect the chassis wiring ground to the core support to extend the common ground for the entire electrical system all the way back into the instrument cluster crossbar ground, and rearward via the rear harness.

The relay mount ground wire and core support is a common ground for the horns, forward lamps, headlight motors, telltale lamp switches, etc. 1964+ optional K66 transistor ignition also uses this common ground point for TI module ground via a jumper wire to another bolt through the core support, all tied to the horn relay mount bolt ground.

The colorized diagram has a note, "All Ground" which means it is common to the chassis ground/Battery Negative. Unfortunately it does not show the physical wire also part of the the harness, which may add confusion, but it does connect to all common grounds in the electrical system.

As we know since the body of the Corvette is not electrically conductive, the design required extra effort to provide several ground points for the electrical system. The horn relay mount bolt is just one of many.

Rich

[Matthew T.]

Re: 65 engine wiring harness short

Matthew,
radiadtoe
--cut--

The colorized diagram has a note, "All Ground" which means it is common to the chassis ground/Battery Negative. Unfortunately it does not show the physical wire also part of the the harness, which may add confusion, but it does connect to all common grounds in the electrical system.

--cut--

Rich

I really don't want to throw anymore confusion in since I'm referring to a 63 and the post is about a 65. I have no 65 diagram only a 63 to look at. Your "All Ground" comment really says Alt Ground not All. In fact the B/W wire does in fact go from the Alt GRN to the Regulator mounting bolt. NOT the horn relay....on my car. That's how the 63 shop manual has it routed. The color diagram has it going to the Horn relay.

I suppose either can be used because both parts are mounted on the metal radiator support. I would also choose the Regulator in case continuity failed at the Horn relay I think better to be on the regulator.

Again I only joined here because it was stated the error included the 63.

Here is my 63 horn relay with a mounting bolt into the metal support. Everything mounted there is grounded by association.

[Richard M.]

Re: 65 engine wiring harness short

Matthew, I'm glad you noticed and asked about grounds. I made some assumptions and now it caused me to investigate a bit more. I know this thread started regarding Brian's '65 but grew into grounds discussions too. I think it's worthwhile to fo

Oh, and yes I misread "Alt" vs "All". Thanks for noticing that.

More 1963 AIM research does show that the harness ground from the Alternator does not go to the Relay mount, only the Regulator mount, as your car is wired. Good reference. I also looked at a photo of my '63 VR and relay and found the same.

Yes your colorized diagram shows the ground wire noted "Horn Relay" instead of the VR ground. A Typo on the diagram.

For reference here are the AIM pages.

1963 Sec 12 Ground at VR top mount bolt.
1963_Sec12_B4_VR_HornRelay.jpg
1963 Sec 6
1963_Sec6_C8_VR.jpg

I also checked the 1964 AIM. That year they added a separate ground wire between the Relay mount and Regulator, which moved from the core support to the inner skirt. The ground wire went to a separate hole on the VR, not the upper mount bolt as done in 1963.


1964 Sec 12 Ground wire added VR to Relay.
1964_Sec12_A8_VR_HornRelay.jpg
1964 Sec 6 Wire shown.
1964_Sec6_A8_VR_HornRelay.jpg

In 1965, they continued to change the ground wiring as I first noted earlier in the thread. A work in progress.

Rich