Kingofl337

My dash lights are very incosistant. If I turn my headlights on, with the car off, they are pretty much off completely. But if I start the car they start to show up a little. If I rev the car they get to about "normal" brightness then dim again. Then if I turn the car off they get a little dimmer then idle. But, at least they are on unlike intial start up. They dash voltameter says 12.5-13ish volts. My multimeter's battery is dead so I haven't check the exact voltage at the battery.

For a side note when I installed the motor this weekend I used 12gauge wire and ran it from the alt, block, UIM, and firewall to the negative on the battery. I figured a rx-7 with good grounds is a happy 7.

Question: Does this shound like a problem with the light switch or ground for the lighting?

YearsOfDecay

Hmmmm..... sure you didn't create a ground loop somewhere when running all that grounding????????

when you have car running at around 2K.. there whould be around 14V across the battery terminals.. at idle.... should be above 12.5 (our alts don't function that well at idle speeds)

Kingofl337

Ground loop?

The the purpose whats to make sure that the grounds are solid and have good connections for the sensors on the engine. Seems to have worked well enough it idles well and no ground related problems yet.

vaughnc

Just to confirm, you've turned the "illumination brightness" dial up all the way.

Kingofl337

no........YES! Man! Gets em every time!
Yeah, I checked it and it works flawlessly. Minus the whole lots of power and lighting up thing.

WAYNE88N/A

Couple of things- most meters don't need a battery to check voltages. Batteries are for resistance readings and continuity checks.

I don't know how many times I'm going to have to repeat myself about this subject, but most of you guys have no idea what you're doing when you add grounds to the car. The alternator to battery ground is a particularly dumb thing to do, because you don't understand circuit theory. What you're doing, in effect, is feeding the battery directly at the expense of the rest of the car's systems, particularly the ECU, but including all other chassis grounds. Remove that one, at least, and see if your problems get better. I'll say it again, for all the newer guys that haven't had a chance to read my previous rants- Clean up the existing grounds on your car, do not add new ones to "fix" problems...

SAiamNE

Where excactly are these grounds?

WAYNE88N/A

Last page or two of the FSM wiring manual shows the locations of all of the OEM grounds...

I must add, so I don't appear to be a total hypocrite, that I have added a couple of BONDING jumpers to my car (most of you would call them grounds, but they are not installed to alter the normal current flows of the OEM grounds). One is a jumper from the rear rotor housing ground directly to the firewall (so the current from the big battery ground, when the alt is off line, does not have to make its way through the starter, tranny, rear housing, and rear rotor housing mating surfaces, but instead takes a route from the main chassis ground on the left strut tower, through the chassis metal), and the other is from the alt mounting bolt to the forward TB mounting bolt/rat's nest (when alt is on line, this electruically bypasses the alt mounting brackets,water pump housing,front housing, front rotor housing, center housing, and rear rotor housing mating surfaces to the rear rotor housing ground).

The only reason these jumpers were added was because I used a crapload of halomar on the rebuild (in the seal grooves), and was concerned that the housings' metal-to-metal contacts may be compromised.

Any wire you add (alternator to chassis or battery is a good example) that changes the current paths from the OEM setup is not a good thing. Any wire you add that helps conductivity in an existing OEM current flow setup (the bonding jumpers bypassing the housings for example) is a good thing...

Kingofl337

Well, I don't know what to tell ya. But, your working against Kevin at rotoryres. He says to do exactly as I did Link I'm fairly proficent with electrical, and I can see there would be more resistance from the alternator to the battery throught the block to the starter ground. I'll get some batteries tonight and check the resistance to the alternator. I'll also disconnect my grounds and see if it helps my problems.

I have an evil digial Fluke meter and it seems to like batteries to light up that LCD thing.

Also based on your sumation oh how could grounds on your motor not be anything but perfect? Alt -> Water pump housing -> Water pump bolts -> Front Iron -> 16+ tension bolts -> Starter Bolt -> Main Ground Wire -> Battery ?

WAYNE88N/A

Or look at it another way- corroded bolts/threads full of oxidation (that does not conduct very well), gaskets and RTV between the water pump housing & front housing (does not conduct at all), oil on the tension bolt threads, and under the rubber o-rings (recommended during the rebuild-same thing, no conduction), halomar between the housings, etc...Start to get the picture?

Quit thinking of a ground as being merely a point in a circuit, and start thinking of it as being a power source for the circuit (and think of that engine block as being one big wire).
Where does the ECU get its power from while the car is running? The rear rotor housing ground. OK, where does that ground get its power from? The alternator frame...You see how this all sounds ***-backward from what is "common knowledge" (most would say that the ECU gets its power from the 12vdc input at pin blah-blah). Yet this is exactly how to visualize circuit flow theory for design purposes.

Why is the ECU's ground out on the rotor housing, wouldn't have it been easier to just bolt the ground wires near the ECU at the factory? Look at the location- damn near 1/2 way in between the big ground at the starter, and the alternator. Start making sense now?

The only other person I've heard on this forum that seems to understand this circuit flow concept is Aaron. It's actually strange trying to convince guys that what they think they know about electricity is all wrong, I realize that, lol, but the facts remain...If the car starts running like **** after a "ground party", you now know why

nhruby

FWIW, I've been lurking and have read most of your posts on this subject Wayne and you convinced me. Cleaning the OEM ground is next weekend's project (and the first time I've ever poked under the hood with more than a dumb look)

Much thanks for all of your posts and wisdom!

Kingofl337

Wayne, after some thought and looking around it seems that Mazda seems to like using the ground to energize items in the car. Injectors for example. But, giving the ecu a clean source of ground is harmful? I guess I don't understand that. Can you enlighten me in that field.

It makes sence that most of the sensors need ground to opperate. Many based on resistance figures. But, when you build a circuit with DC voltage ground is supposed to be a common pole. Your run the hot to the device and then can ground negative pole. This allows for less complex wiring because you can eliminate a leads to each device. Saving in wiring. I've never seen anyone build a machine and say oh I used these ground for current flow? I'm willing to learn but need some help making the jump.

WAYNE88N/A

The only thing Mazda did backwards from the way most of us would like is their voltage checks at various locations (including the ECU). We are used to checking for voltages BEFORE the components in a circuit, i.e. if we have voltage there, then we have power up to that point. Happens to be the way I've been troubleshooting aircraft and cars for 2 decades also, so I was confused at first too when troubleshooting the RX-7 per the FSM steps.

Mazda likes to take voltage checks AFTER the component (on the ground side of the circuit). What this means is if you have voltage at this point, the circuit is de-energized (the "switch" in the circuit is not on, therefore the component is not dropping the voltage). 0 volts means the solenoid (or whatever) is energized, 12v means it's not. Totally backwards from what you'd expect.

As far as switching the ground on & off to energize a circuit (injectors are a good example), that's not really confusing, if you consider that it doesn't matter where the switch is located in a circuit- we're just used to seeing them on the positive side of the circuit, before the component, not after (as viewed on a schematic).

Mazda's OEM grounds also disappoint- I've covered this in detail on the "electrical troubleshooting for the RX-7" thread a while back. It's not the location of the grounds that's the problem, it's the way that the hardware was used to ground the circuits...

And no, Kingo, giving the ECU that chassis ground shouldn't be a problem, as long as the car is bonded properly (in other words, the negative ground "potential" has to be the same between the engine, chassis, and all grounds on the car. All OEM grounds and bonding jumpers (the tranny-to-firewall wire being a good example) must be in top-notch shape for this to be feasible. In fact, I've been helping a fellow rotarite for months now on an intermittent start problem, and grounding the ECU to the chassis was one of the troubleshooting steps I recommended. So it's not a sin, but with good OEM grounds (and harnesses), it shouldn't be an option.

I lost you on the circuit flow stuff, lol...Suffice to say that you can't just think of the positive wiring on the car as powering everything, and the grounds somehow being "dead", because when the circuit is energized, the current (but not the voltage) is the same in both branches. The analogy I'm using of picturing the grounds as being the "power" wires is to get you guys to open up your minds to the fact that when you install "new" ground wires on the car, you are changing the circuits on the car as designed by Mazda. And their electrical engineers had a hell of lot more schooling in circuit design theory than we do, eh?

Why do you guys make me type so much, lol

Kingofl337

Because your evil.