Electrical issue on 73 240Z Help please

[DR1FT10]

I had an electrical short come about. A little below the battery I have a relay? or something like it, that burnt up. The car died on me and wont crank. The relay? has a 4 wire plug and is mounted to the firewall a little down and to theside of the battery. I went and looked at another 73 and it had a 6 wire connector and the relay? was smaller. Haynes wiring diagram does not show this anywhere, I'm not good withnwiring so might be wrong on that. The wires are black and white, black and yellow, and white and black and either the BW or BY has 2 wires in connector. Can I bypass this relay? and what is it for. Please help! Thanks

[zKars]

The FSM for a 73 can be found at xenons30.com under the reference link. Haynes diagrams are rarely complete and representative of all teh changes. Every year the electrical changed in a significant way.

Looking at the "Body Electrical" document, Page BE-2 that manual has a diagram of all the "stuff" in the engine bay. Sounds like that relay is #18, the Throttle opener relay, Manual trans only. The six wire relay on your other car might be an automatic, ie part #17, seat belt relay. BE-5 has the whole schematic, it looks like the BW wire goes directly to the ignition switch, and as such if the relay of blown, may be cause of your problem. Check all the fuses and the fusible link. Try removing/unplugging the relay and see if that helps. Its not critical to operation.

In any event, it can very likely be replaced with a standard Bosch type relay. Its a simple two terminal coil and two terminal switch function. Unfortunately the schematic does not have the wire colors other than the BW and GB so it will take a bit of sleuthing. Good luck

Oh and what does it do? Seems a speedo sensor turns on this relay, which accuates a vacuum device which likely opens the "throttle" more.. Don't ask me why... I bet its emmision related.

Edited August 23, 2012 by zKars

[SteveJ]

I do believe you're talking about the voltage regulator. It's not a relay. You cannot bypass it unless you also install an internally regulated alternator. And since you have a 73, if you did get the internally regulated alternator, you would also need to disable the relay for the electric fuel pump. Just saying...

It would probably be easier to replace the regulator. Hopefully, you don't have a problem with your alternator that caused problems for the regulator.

[5thhorsemann]

Not the V reg. That mounts up by the alt. There was a thread about a year ago regarding this device, I seem to recall it is an emission related part but I don't remember what it does. I just unpluged mine and it didnt effect the car starting at all. FWIW

[DR1FT10]

Thanks for the help and the website, she's running I'm at peace again.

[emptech]

Mike:

I know you got it fixed, but it seems like a fusible link from your description. Has four pins, if you take the cover off

you probably found two wires, each one like an inverted U. One was probably fried. What is more important, what

was the cause of the link blowing? A fusible link is nothing more than a piece of wire of a specific gage that gets hot

when there is too much current and it burns open, nothing more than a fuse in effect.

Jim

[SteveJ]

Mike:

I know you got it fixed, but it seems like a fusible link from your description. Has four pins, if you take the cover off

you probably found two wires, each one like an inverted U. One was probably fried. What is more important, what

was the cause of the link blowing? A fusible link is nothing more than a piece of wire of a specific gage that gets hot

when there is too much current and it burns open, nothing more than a fuse in effect.

Jim

The 73 does not have fusible links arranged in that fashion. The 260Z was the first to have a box for the fusible links. The 73 has a single link coming off of the starter.