How I installed a starter button in a 512TR

Many TR owners have had problems with no-start in hot conditions. In my 1994 512TR I traced the problem back to the fusebox. Many years ago I installed a relay at the starter solenoid which worked well for 30K+ miles but eventually led to catastrophic starter failure when enough voltage leaked into the circuit to fire the relay while I was driving.

The real answer to this problem is to perform the Dave Helms gold connector upgrade, but until then I propose an auxilliary starter button as a temporary solution.

Let's review the starter circuit on a 512TR. Power comes from the battery to the ignition switch. With the key in START position, power travels from the ignition switch via a white wire to Connector I, position 1 on the fuse box and magically exits the fuse box via another white wire at Connector F, position 1, and from there via the wiring harness to a round connector under the driver's side rear fender and finally to the 12V connector on the starter solenoid itself.

My first modification was to place a jumper wire from (I)1 to (F)1 and this did seem to help. You can not just remove the (I)1 wire from the plastic connector because it also serves as ground to other circuits (turn signals, flashers, etc). I still would occasionally have to pop the hood, open the fusebox cover and jiggle the connectors to get her to start (very embarrassing).

I went on EBay and found a tiny momentary-on button (there are many start-button kits on EBay and Amazon complete with relays and instructions as well as many YouTube videos that describe the installation).

I have a bunch of heavy duty relays and holders and I had previously installed a dedicated power cable and junction box for my Dave Helms Fusebox Conversion. The 12V power in to the relay came from the junction box which was previously mounted in the AC dryer compartment. Ground to the relay came from a mounting bolt for hood latch(see photos). 12V power out to the starter was routed through the AC hose grommet into the fuse box compartment and then to the white wire going to the starter out of (F)1.

I located the switch next to the radio, so it could not accidentally be pushed while the car was running (very bad). I drilled a small hole (5/16") and then poked around with a piece of aluminum welding rod until I found a passage through to the back of the fuse box compartment (easier if the fuse box and the secondary panel are removed first). I then taped the push button wires to the welding rod and fed them through.

One of the push button wires needs to be hooked to an ignition-ON 12v source (I chose the top 3rd fuse from the driver's side on the fuse box) and the other push button wire is routed along the back of the fuse box compartment, through the same AC grommet and into the dryer compartment where it is attached to the 12V actuating wire to the relay.

All connections were soldered and heat shrink wrapped and neatly tucked away. The relay was mounted as shown.

Now, if the starter ever fails to turn over, I merely open the radio hatch, push the magic button and nobody is the wiser.

I hope this helps.

Photo 1: White jumper (I)1 -(F)1 with purple relay wire temporarily attached. Note black push button wire at 3rd fuse from right.
Photo 2: 12V power junction box from battery and power-IN wire to relay
Photo 3: Ground attachment
Photo 4: Junction box and relay secure in place. Note two wires following the AC hose through grommet into fuse box compartment
Photo 5: Dryer compartment all cleaned up.
Photo 6 and 7: Push button installed
Photo 8: Fuse Box neat and tidy
Photo 9: Push Button
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login

 

That might just work, Turbo-Joe. I wonder if the starter turning over the engine and generator would make enough current to kill the relay before the car started???

 

So, I would leave all other connections as described above, but route relay ground (minus) to the alternator control lamp? Sounds easily do-able. Turbo-Joe, do you know where the circuit to the generator control lamp can be found? I wonder if there are any other electrical circuits connected to that lamp?

 

What circuits do these wires energize?