Hi and thanks for viewing
I have a 1987 Rx-7 N/A 5spd

The problem is the battery is going dead, slowly.

At first, I exchanged the 11yr old alternator
(It had a lifetime warranty and was put on 11yrs ago)
The alternator bearing or brush was making squeeling noise
I also had the battery charged at this time

Right after I put them on, I tested per the alternator instructions and they all tested O.K.
(Test the cables, the B post output, the frame test, battery&headlight, etc) all tested O.K. for the alternator instructions, but the in the car volt meter did not go much past ~13volts

I then drove the car home (240miles)
The next day I retested and the numbers were too low to pass the same test
So I search on here and found how to test current draw with a multi-meter
(Negative bat. cable disc. and hooked up to posi. MM cable, neg MM cable hook'd to negative bat. post)

All fuses were good except the BTN fuse was pulling .9 or 983

depending on the setting (200m and 20m setting for -- http://manuals.harborfreight.com/man...8999/98025.pdf this meter --)

So I search on here and found the 2nd row on the inside fuse box and the ABS (car does not have) is the BTN fuse

With the MM still hooked up I discovered that the HAZARD fuse was the culprit.

Unplugging the HAZARD fuse the reading the MM goes to 0

So I search and see maybe the CPU is the problem or maybe turn lamps are. I know the rear tail lamp was recently replaced so I looked and unplug the connectors (on both tail lamps) and still check the MM. No change.

So then I unplug the CPU
(online FSM 15-23 A the plug that goes into A; turn and hazard unit)

The reading on the MM goes to 0 instantly.

So I know the if I unplug that connector from the CPU I lose the current draw.
Note: I did not check the front turn lamps and don't recall off hand if the hazards do work

I've seen posts about re-soldering the CPU
My guess is the CPU is trouble, or the front lamps are trouble

I don't know what to do now (still learning electronics)

 

I wouldn't be surprised if it is in fact your CPU that is giving you issues as I had the same problem on my S5 except it immobilized my car due to the factory alarm being in the CPU.

I suppose another way to eliminate the possibility of a bad switch would be to unplug the switch that houses the hazard button and see if the current draw goes away. Do the same for the turn signal switch. The CPU supplies the power to the above switches and the switches ground off the power to complete the circuit, which then activates the flasher unit inside the CPU and directs power to the turn signal lights. (from what I can tell in the FSM).

The lamps themselves can't cause a current draw unless they are getting small voltage. Other components do run through the CPU too....

If you do need to fix it, I would recommend just get a new one from Mazdatrix. The new one I got was very different from the stock one on my S5, better built.

 

Focus on checking voltage on the wires which are a part of connector "F-55" while connected to the CPU except for the B/L wire and the Black wire in the plug and see what this turns up.

 

So I was able to pull the cluster and unplug the turn and hazard switches. The draw did not go away. I also was able to unplug the turn cancel sensor but that also made no difference.
I wasn't able to look at it further because it started raining

I pulled all 4 plugs off the cluster, but wasn't able to use a voltmeter on the cpu

 

Also, check the Black ground wire connected to the circuit board. The Black/Blue wire should have constant voltage but "none" of the other wires should when the hazard/flasher unit is not in operation.

 

The gnd from the HAZARD switch to the CPU is thru the plug called CR-01 which is ...........the WIPER and WASHER switch. So if you just unplug the wiper switch that should do the job of eliminating the Hazard switch as a problem.

That CPU board can be bought from MazdaTrix in lieu of buying the whole CPU.

Bothered a bit by something you wrote. The BTN fuse is in the engine bay fuse box, not the interior. Maybe I just misunderstood. Not important. The BTN fuse is 60a and feeds batt power to the top row of fuses in the interior which are on the.....batt buss on that fuse box.

Maybe pull the BTN fuse at the end of the day til you get a new Hazard/turn signal board for your CPU?

 

I understand what you're saying to do, but how do I physically check the voltage with my multi-meter? The wires are so small I don't think I could get both of the multi-meter probes on them. Do I have to back-probe them? I'd have to buy something to back probe them or would a paperclip or similar work?

I took out the 'cluster' (the shaded area in picture on page 15-10)
I unplugged the 4 connectors that plug into the switches (marked as 7 on 15-11/12)

I also unplugged F-16 on page 50-60

Also, yes I didn't specify but the BTN fuse I checked was in the engine bay, then I checked the interior fuses that correlate to the BTN fuse

Thanks for the ideas so far

 

With the meter set to vdc you would take the red meter lead and back probe the wire in the plug that you want to check, which needs to be connected to the CPU when doing this, and the black meter lead needs to be placed on a known grounding source. There is a plastic panel located on the very front of the center console, driver's side. It has a screw or two to help fasten it into place. Remove the screw(s) and also be aware of the plastic clips that are part of this panel that help keep it in place and remove this panel. When done pull the carpet away and it will expose a bolt that is used to hold the console in place. This is a good ground source in case you cannot find a good ground point to work with.

Also, have you verified whether the hazard/flasher and turn signals work even though you have a voltage draw?

And remember to check the Black ground as well.

 

check the bulbs to see that you are using the Correct Bulb for the Bulb that you replaced.
If you Mistakenly put is a single filament bulb in a dual Filament slot,it will Really screw with your Electricals..

 

So I did the backprobe as you said

50-61 connector f-55 the LG wire pulls .3
I checked all the other wires,
the only other one to pull is the B/L which also pulls .3

I'm confused though, looking at the picture and following the arrow it runs to the hazard switch. I unplugged that switch though.

Does that mean there is a short in the wire?

What does this wire do?
Is it just for the hazard flashers?
Could I just cut it and tape it off?

It looks like a wire from the control unit runs into it also

Edit: I know the turn signals work, but I don't know about the hazard flashers

 

LG wire becomes a ground wire when the red hazard flasher button is depressed and it tells the circuit board to turn the hazard lights on. The connection to the "control unit" would be the factory alarm system if equipped. With the plug you have disconnected is there still a current draw?

When you say the B/L wire pulls .3 I'm assuming you mean amps for with respect to voltage it should be 12 volts.

And don't cut that wire!

 

With the hazard plug (the one in the cluster that goes to the button) disconnected it still has a draw. When you disconnect it from the CPU the draw goes away

The .3 reading was in DCv not amps
Both the wires read .3

 

If the plug F-55 is disconnected and you checked for voltage on B/L it should indicate 12 volts. What does yours show? And does your car have a factory alarm?

EDIT: And since you're in the area try removing the 7.5 amp Meter fuse and see if the amp draw is still present. Just curious. This is if you have the factory alarm and not otherwise.

DOUBLE EDIT: I'm assuming you are doing these diagnostic tests with the BTN and Hazard fuse plugged in!

 

Well, I have some definite results this time, although now I feel rather amateur


First, I retested the voltage in the F-55
I moved my ground around until I found one that gave me a 'good' reading
The B/L wire showed 12.41->12.39
The LG wire showed 2.86low and 3.05 high
The interesting part, when I tested the voltage of the LG wire (backprobe the positive and grounded the negative lead) the hazard lights would flash and make the 'clicking' sound
They flashed inside the car (in the instrument panel) and outside the car (the rear flash lights)

Second, I decided to re-check the current draw
It was the same

Third, I wanted to test the amp draw with the room fuse out (I thought I had tested this before and it made no difference)
when I pulled the fuse out, I noticed this time (not the first time though) that the fuse was burned out

My fuse box looks like the cover in the 2nd gen FAQ
except I have NO 7.5 fuses and instead they are 10A fuses

I used a spare 10A fuse and swapped it into the room fuse 'location' and some things happened
The open door beep came on, the idiot lights turned on
When I tested current draw (all fuses in)(no tests have been done with a key in) I got 3.5-3.6 amps on the 10A setting
Pulling the room fuse out I got 0 amps on the 10a setting

Also, with the fuses in I tested the cluster connectors
15-11/12 number 7
Note: the connectors that plug into the actual buttons/switches
the 'bigger' one had voltage present on 5 wires
the smaller one had voltage present on 2 wires
on the right side
the 'bigger' one had voltage present only on 1 wire, which made the hazards flash
the smaller one had no voltage on any wires

 

Room fuse feeds the ECU pin 3J or 3I batt voltage 24/7. Car will run without this fuse working and feeding the ECU. It must be a memory feed of some sort that does not effect driving.

 

....

 

I was hoping this would be more of a 'common' fix problem that I had overlooked but it seems it's going to take more work on my part

The original problem was that the alternator was charging but the battery would drain. The other problem was that the volt meter would not go past ~12.5 volts, although the alternator was producing more than that.

The PD had failed and the car had caught fire, and the engine wiring harness had been replaced. The ECU had a noticeable 'burn'/'short' in it so it had been replaced.

I need to investigate further into the room fuse and find the drain, and hope that no other components have shorts in them
Thanks for the help up till now I'll still be working on it any ideas would still be appreciated

 

When you pulled the Hazard fuse it stopped the drain. Then you stopped the drain when the Room fuse was pulled. The Stop, Antenna, and Illumination fuses are all apart of the fuses which are powered by the BTN fuse in addition to the Hazard and Room fuses. Besides the Room and Hazard fuse, do any of the other fuses listed stop the amperage drain?

The Room fuse powers the idiot light clock, ignition key reminder buzzer, alarm, radio, courtesy lights and pin 3J of the ECU and that's all.

 

Remember, you probably have the doors open when you test the ROOM fuse circuit. You will have a current draw... Just wanted to list this if you didn't already think about it.

You want to see what is really drawing a drain, not just the small stuff...

 

ROOM fuse to the 3J has a current draw 24/7 and its draw is in miliamps.

ROOM is fed by the BTN....along with all the other fuses on the interior batt buss.

 

Does your car have the factory alarm? Yes or no? If so, the alarm would connect to "both" the Hazard fuse and the Room fuse. If the alarm were the culprit, this would help to explain why if you pull either fuse why the drain disappears. Just a thought!

 

And this is the same issues I had with my CPU to the point I was left stranded (see my first post)...

 

Or..............no factory alarm but someone has tapped into the alarm wiring to feed some aftermarket device. Or some aftermarket devive is tapped into the wiring the Room fuse supplys power to.

The ref I made to the Room fuse feeding pwr to the ECU in mv 24hrs a day was just some FYI that you might not have known about. I think its been posted a few times on this forum that the current draw of the ECU thru the Room fuse with key OFF is something like 40-50 ma. Memory.

 

I got curious. I put the meter to my battery negative cable as shown in my jpg a few posts above. Key out of the ignition.

Read 9ma with all fuses in.

Pulled ECUs small plug and it dropped to 6ma.

Pulled ROOM fuse and it dropped to 1ma (surprised me, I thought it should go to zip).

Pulled HAZARD fuse and the 1ma went away and I had zero on the meter. Soooo the Hazard circuit doew draw some current on my car but not enough to give a thought to.

And no, I'm not going to pull the plugs off the meter surround for anybody so don't ask.

 

What about "pulling" that field of Poison Ivy you have with key in pocket.