Hi,

I've just fitted some CSG bumper lights on my 1999 FD and upon depressing the brake I notice that the lights dim significantly.

Having read a few threads I think this might just be bad grounding and I'm looking at how to resolve; is this the likely cause or should I look for any other issues?

The car has had the battery moved to the boot and I have to say I'm not overly impressed with the install i.e The current ground from battery to chassis is through the bolt that holds the rear seat back down and I think this is a pretty poor

Need some advice on how to change the wiring to improve the grounding. My thoughts were either to drill a new hole to mount a bolt, and to remove the paint around the hole before clamping the ground with a new bolt to the body, would this be sufficient? Are there any pre-tapped holes in the boot area that I could use for this?

Should I run a new ground from the boot to the firewall and ground at this point or is this overkill?

Also read that I might need to do a bit of maintenance on the grounds throughout the car to clean each mounting point and to replace any degraded wires once I inspect them, is there any particular wire solution to replace them or should I just replace like for like?

One site I read suggested using stainless bolts, but I'm a little worried about galvanic corrosion, anyone got any experience?

Thanks

Richard

 

welcome to the board.

was there any inkling of a problem before your installed the bumper with the LEDs?

1. what gauge cables were used for the install at the battery and alternator?

2. is there a ground extending to the engine block anywhere as well?

3. i'm sure other guys better-versed in FDs will give you more solid advice, but if you do decide to go with drilling your own, i don't think there's any need to remove paint for it. the factory didn't.

4. i really, really dig your screen name.

have you seen this: https://www.rx7club.com/3rd-generati...-trunk-918093/ or the write at Regan Rotary Racing?

 

Thanks for the welcome. Put some responses in red below:

was there any inkling of a problem before your installed the bumper with the LEDs? No dimming I noticed but the radio go quiet while braking after high revs

1. what gauge cables were used for the install at the battery and alternator? I'm not sure what gauge the previous owner fitted but the ground is not even in contact with the body, just a mount that is sat bolted over the seat back mount, think this might be one issue.

2. is there a ground extending to the engine block anywhere as well? Don't think any standard grounds have been removed so should be from what I can tell of the wiring diagrams

3. i'm sure other guys better-versed in FDs will give you more solid advice, but if you do decide to go with drilling your own, i don't think there's any need to remove paint for it. the factory didn't. Cool, can always test it and improve afterwards if there is any issue I suppose. Think I'm going to get a proper bolt in cable mount for my new 0 gauge cable, which I think I'll run direct to the new starter I've just acquired.

4. i really, really dig your screen name. Thanks

have you seen this: https://www.rx7club.com/3rd-generati...-trunk-918093/ or the write at Regan Rotary Racing? Yes I've read that and it made me decide to re-fit the wiring and sort out the install, but would like to know whether I should just bite the bullet and also clean up all the normal grounds.

 

If you have a multimeter check the voltage at the bumper lights to see if there is a significant voltage drop. If there isn't then the problem is with the lights.

Leds are very sensitive to voltage differences so a voltage regulator is commonly used. If a voltage regulator isn't used then you will see the leds dim and brighten up when the voltage fluctuates. This will also cause leds to prematurely fail.

 

If it ever stops raining when I go out to work on the car I'll stick the multimeter on them and get the missus to depress the brake. Joy of the good old British weather that I haven't had a dry weekend when the missus has been present.

 

That's funny, women and weather, the down fall to car overs every where.

 

I get the feeling that the Main Ground is suspect, considering the multitude of symptoms in different locations in the car. Logically, it would be the one common factor amongst the circuits in question here.

Proper RX-7 Grounding Procedures

If the ground is not attached to BARE SHINY METAL, it acts as a resistor (Ohm's law) so the whole circuit gets less power and you get dim lights, quiet stereo, slow starter, etc. Also, if it is anything like a FC, there is little reason to drill more holes when you have plenty of holes to use (That's what she said ). Just clean it really well and run a bolt up from the bottom to work as a stud so it doesn't draw crap up into the connection on removal. On my FC, I re-used a rear seat bolt hole for the ground cable and it works beautifully.