Could use some help with Lacy (Miata content)

I am having a few issues with the Miata right now. She's a 1994. Here's what's going on:

Fuel gauge doesn't work anymore. This happened while at a track day. I assume vibration caused something to go kaput. It should be known that 4 months before the said track day I had the fuel pump (and assembly) out of the tank.

I took the gauge cluster apart (as much as I could) and tried unplugging and plugging back in the gauge. Also, for about 25 seconds in mid-February, the fuel gauge turned back on. But then it went back off again and hasn't come back.

Also, my reverse lights no longer work. I replaced both bulbs, but to no avail. They are the right bulbs. I looked through the manual for the fuse number, and the best one I could guess also ran the headlights and they work and the fuse is fine.

Lastly, the right turn signal is getting fritzy. Occasionally, it'll blink at double-rate (indicating a burnt bulb). I confirm this by noting that one of the bulbs on that side is out (but the other works). However, it does this intermittently. As of tonight, all four bulbs work just fine.

Electrically, this car looks like it's in for an overhaul, but this I hate electrical work more than anything. You practically have to disassemble the whole berkeleying car to fix one broken wire (Remember my fuel pump wire issue? Yeah. I had to run a new wire from the solenoid under the dash to the pump.).

Oh, and the cruise control went out for a couple months, but now works just fine. The HVAC fan also needs a slight tap to stay on.

Grounds grounds grounds. When you've got this many weird electrical problems, it's almost always grounds.

The turn indicator thing, maybe not. Pull the turn signal relay module and look inside. They'll crack solder joints and act exactly like this. Heat up the offending joint with a solder gun and let it re-flow around the connector, problem solved.

Are the reverse lights getting voltage? If you've recently done work on the transmission, you have to unplug both the neutral switch and the reverse light switch. Or more accurately, you need to plug them back in again :)

So, you had a fuel pump wiring problem and now you have a sender problem? Those two wires run together for much of their length.

Keith wrote: Are the reverse lights getting voltage? If you've recently done work on the transmission, you have to unplug both the neutral switch and the reverse light switch. Or more accurately, you need to plug them back in again :)

I've seen the switch go bad, and I've seen the wires crossed (so the reverse lights come on in 5th gear!) New switch is pretty cheap from Mazda.

you guys are Heros. One of the previous owners did a lot of electrical changes in the car: fog lights, A/M headlights, and probably more. I'm sure this all relates to what he did. And keith, you're probably right: I'll start checking grounds.

Thanks!

Wowak wrote:

Keith wrote: Are the reverse lights getting voltage? If you've recently done work on the transmission, you have to unplug both the neutral switch and the reverse light switch. Or more accurately, you need to plug them back in again :)

I've seen the switch go bad, and I've seen the wires crossed (so the reverse lights come on in 5th gear!) New switch is pretty cheap from Mazda.

Where is the reverse light switch? Is it under the car or inside?

I know this is from my last neon, but these are a few basics i have dealt with. When I had a similar turn signal issue, it was due to a loose socket, replace the socket and it worked fine for the rest of the time i had that car.

I have also had issues with the reverse light. I pulled the switch from the transmision and manually activated the switch and it worked just fine, so in my casethe part in the transmission wasn't hitting the switch. But if wowak is talking about crossed wires and if coming on in 5th, then all bets are off with this little bit of advice.

Just my $.02 even thoe it came from a totaly different car

The reverse light switch is known to fail on miatas, mine was bad. Fortunately it's about a $20 part from rockauto, and it's pretty easy to change. It's located on the driver's side of the transmission.

It's the gizmo with the red wires pictured:

I hope your car is named after the girl in Caddyshack.

Keith wrote: Grounds grounds grounds. When you've got this many weird electrical problems, it's almost always grounds.

Keith beat me to it. I fixed a few "old German car" electrical weirdness's by finding, cleaning and securely reattaching ground wires.

Ahh, thanks for the picture MCarp.

Type Q, it looks like I've got myself a weekend under the dash, don't I? Ha. My least favorite place.

Yup, Mike's pic is right on. As for grounds, Miata lore has it that most grounding trouble comes from the common ground on the left front support under the master cylinder (in the engine bay. Has eight black wires going into a plastic connector-looking bit then an eyelet that is bolted to the chassis.) Dripping brake fluid causes it to rust. Many have had luck cleaning it and attaching it to the firewall or one of the mounting points for the junction box under the left front fender (you'll see it from the engine bay.) If my digital camera weren't on the fritz I'd go take some pictures.

Also in regards to the reverse light switch. Notice in Mike's picture that there are two male prongs on the leads coming from it. They connect to a harness that comes over the top of the transmission from the passenger side (and IIRC is connected by tabs to the powerplant frame.) Its possible they've come loose or were never reconnected after a repair. Its alot of fun to lay under a Miata and basically hug the transmission with the male prongs in one hand, and the female connectors in the other, connecting them by feel because the trans is right in your face. Have fun!

I saw the plastic connector with the 8 ground wires when I was looking around yesterday. It looked pretty good and it was secure. But I didn't unbolt it to see if there was any rust. I meant to ask about it actually. I will look at this over the weekend to see if it rusted.

Also, the reverse lights just decided to stop working in February. I think it's the switch, but I'm going to check those out as well. It wouldn't be the first time I've seen something come unplugged (insert witty Family Guy flashback here).

Edit: Giggedy!

There's no polarity to the reverse light switch. I have no idea how the "plug it in backwards and get reverse lights in 5th" theory is supposed to work.

For grounds, check the engine grounding strap. The ground on the PPF back near the diff is a really important one overall, although I'm not sure it's going to start causing signal problems - more likely to cause a "car no workie" problem from what I recall.

Keith wrote: There's no polarity to the reverse light switch. I have no idea how the "plug it in backwards and get reverse lights in 5th" theory is supposed to work.

I explained poorly. There are two switches, and their connectors aren't compatible, but you can swap them back and forth in regards to their position on the transmission. Don't ask me how you screw that up but someone I knew in FL had a car where the switches were reversed.

The other switch is the neutral switch. I can see how you'd get reverse lights in every gear or in neutral only from that one - I forget if it's NC or NO.

Yeah thats what it was. My memory is getting fuzzy and I'm not even 30 yet.

Keith wrote: There's no polarity to the reverse light switch. I have no idea how the "plug it in backwards and get reverse lights in 5th" theory is supposed to work. For grounds, check the engine grounding strap. The ground on the PPF back near the diff is a really important one overall, although I'm not sure it's going to start causing signal problems - more likely to cause a "car no workie" problem from what I recall.

What is a PPF (rather, what does it stand for)? I'll definitely check these though.

Power Plant Frame. Otherwise known as "the big girder that joins the transmission to the differential". Red in this picture.

Cool! Thanks buddy.