1999 - Wife tried welding while driving... now it wont start

Hey guys.

Here's what happened. Wife is driving the car, and the tire jack winds up contacting both terminals of the battery, at the same time, unknown to her. Car quits. I come help, I can get it moving running, but as soon as I take the ebrake off (and light disappears on the dash) it stalls. Got it towed.

Car is 1999 Miata 1.8L 5spd

Symptoms: Car turns over strong, doesn't fire up anymore Dash has no lights No check engine light comes on Power mirrors, windows, etc do not work Will not jump start

Ive tried: Checking "room fuse" & "engine fuse" in interior fuse box Checking and replacing main efi relay (green one) Checking all fuses, including big ones under hood. Checking that ECU connection is tight Replace battery and check cables for damage

Followed this set of processes, only step 2 because everything else seems to be fine. I have not tried pulling codes, but doubtful due to no dash lights.

I would love some thoughts. I'll clarify anything I missed. http://clubroadster.net/vb_forum/18-engine-transmission/86146-my-miata-cranks-but-wont-start.html

Battery and alternator are highly suspect, with the wiring between them.

Did you find & clean all grounds?

turns over under own battery power or with a jump?

Will the computer talk to a scan tool?

Ok, I gotta ask wtf a tire jack is doing next to a battery? Battery in the trunk? Jack not held down? Jack zip tied under the hood?

Battery in the trunk?

Car is 1999 Miata 1.8L 5spd

So yes.

Any power to the fuse box? Not familiar with these but some fuseboxes pull power from the starter with a fusible link?

I say the ECU is fried, probably due to voltage spikes. ECUs have protection against that sort of thing, but they aren't impervious. No fuses will be burnt open because the problem happened right at the battery.

Clean out trunk, secure jack, install known good battery, perform voltage drops to starter, alternator and all major grounds.

I'd try a good, preferably new battery first. Given the fact that you said it won't even jump or go into accessory mode, it's most likely that when the terminals were crossed, the battery fried itself.

G_Body_Man wrote: I'd try a good, preferably new battery first. Given the fact that you said it won't even jump or go into accessory mode, it's most likely that when the terminals were crossed, the battery fried itself.

I don't see how when the OP reported:

Symptoms: Car turns over strong, doesn't fire up anymore

What's confusing is that it "turns over strong" but OP reports

Dash has no lights No check engine light comes on Power mirrors, windows, etc do not work Will not jump start

That seems to suggest something major downstream of the battery, like a fusable link. This make no sense if the short happened upstream of it... unless there's a big capacitive load somewhere downstream, that when the battery was shorted, all that stored energy tried flowing back through the link and burned it open. It's a stretch, but that's my recommendation, check the fusable link first.

Also, you need to start poking around with a voltmeter and see if power is at least getting to the main fuse box. My bet is that it's not.

Cross fingers for a fusable link being fried, but sounds like a toasted ecu to me

oldtin wrote: Cross fingers for a fusable link being fried, but sounds like a toasted ecu to me

That would be my SWAG.

bawward wrote: Hey guys. Here's what happened. Wife is driving the car, and the tire jack winds up contacting both terminals of the battery, at the same time, unknown to her. Car quits. I come help, I can get it moving running, but as soon as I take the ebrake off (and light disappears on the dash) it stalls. Got it towed. Car is 1999 Miata 1.8L 5spd Symptoms: Car turns over strong, doesn't fire up anymore Dash has no lights No check engine light comes on Power mirrors, windows, etc do not work Will not jump start Ive tried: Checking "room fuse" & "engine fuse" in interior fuse box Checking and replacing main efi relay (green one) Checking all fuses, including big ones under hood. Checking that ECU connection is tight Replace battery and check cables for damage Followed this set of processes, only step 2 because everything else seems to be fine. I have not tried pulling codes, but doubtful due to no dash lights. I would love some thoughts. I'll clarify anything I missed. http://clubroadster.net/vb_forum/18-engine-transmission/86146-my-miata-cranks-but-wont-start.html

I have a hunch that the ignition switched circuit is finding its ground through the handbrake switch via the instrument cluster.

FINDING the problem is going to be a little involved, but you'll probably find a burnt or relaxed contact in a connector if you don't see any obvious melted wires.

This is where a tool like a Power Probe is handy, you can check circuit integrity instead of just pulling fuses and eyeballing them. I've seen fuse holders relax and cause a fault, good fuse, good wiring, everything looks okay...

Vigo wrote:

Battery in the trunk?

Car is 1999 Miata 1.8L 5spd

So yes.

I think the jack stores on the opposite side from the battery though...I better check my sister's NB that I've been driving for the last few days.

There should also be a rubber thingy attached to the positive lead from the factory that covers that terminal ...

In reply to bawward:Forgot to say it,welcome to the dark side . Knurled gave some good advice above on the Ebrake switch. Car will run when handle is engaged but dies when released? Do the headlights or brake lights work? Do you have a wiring diagram?

First I have to say - All your responses were VERY welcomed and appreciated! Thank for taking the time. This is a crazy situation. I apologize for my delay in responding - wasn't receiving notifications for this thread?

OK - to start responding...

Knurled : This is extremely interesting... I had never thought of this. Yes, for a couple tries, the car would start and even run... it felt great, idled like normal, no lights on the dash board (this is after the initial "car died, smoke from trunk" incident. However, when the vehicle was idling great, I would release the handbrake to start moving (test drive) and it would die almost as immediately as the "e-brake" light on the dash went away. Since then, the dash has been completely blank w/ no lights, etc. The "key in the ignition dinging" sound does persist... Any specific areas you would suggest first for finding this fault?

GameboyRMH - It does store in the trunk, on the side of the spare closest to the battery. However... the jack leapt across the gap in an effort to commit suicide I suspect...

TRoglodyte - Knurled did give me some great advice... kind of blew my mind... now, how to start tracing it!? So I'm looking for connectors and melted wires... between the ignition and handbrake? Hmmmmm.....

For general clarification and continued puzzlement - I have checked the battery - the car will "turn over" but not start up. I have verified that the interior fuse panel is getting power. The "engine" fuse (which supplies the Main EFI Relay) DOES have power, is good. Then I went to the main Relay, which does receive power from the interior fuse panel. I then replaced the relay (for giggles) and that didn't affect anything. So, I haven't then verified that the ECU is getting juice. If it is, I would assume it's the ECU?

Everyone else - Yes, the battery should of had a rubber cap, but somehow that also was removed from the terminal, just flipped up! Imagine the chances!!!

A new ECU is in the mail... $25 isn't bad. All the other new parts I've bought have been returned, so at this point I'm at net-zero cost. I "hope" it's the ECU.

I'd strongly recommend NOT putting the new ECU in, until you've tracked any and all possible shorts in the system. Wouldn't want to let the Magic Smoke out of another box.

RealMiniParker wrote: I'd strongly recommend NOT putting the new ECU in, until you've tracked any and all possible shorts in the system. Wouldn't want to let the Magic Smoke out of another box.

Good thought - doing some double-checking wouldn't hurt.

bawward wrote: GameboyRMH - It does store in the trunk, on the side of the spare closest to the battery. However... the jack leapt across the gap in an effort to commit suicide I suspect...

bawward wrote: Everyone else - Yes, the battery should of had a rubber cap, but somehow that also was removed from the terminal, just flipped up! Imagine the chances!!!

I think it was a jackicide planned and staged to look like a suicide. I'd be looking at the rubber cap for your primary suspect.

Are you positive it grounded the 2 terminals?

I would assume it grounded the positive terminal to the body, and blew the fusible link.

If its turning over but will only run with e-brake up that where you need to start looking its would seem its grounding or sending power via the ebrake light

SVreX wrote: Are you positive it grounded the 2 terminals? I would assume it grounded the positive terminal to the body, and blew the fusible link.

Agreed.

Also, of note, (but this is a BMW e36, so could be different) that the starter is generally the only thing that does not go through the fusible link. I got my cables hooked up wrong once and the fusible link was good for about 2 cranks of the engine before the amperage fried it.

Essentially what I am trying to say is that the BMW e36 (similar battery in truck situation) had one battery cable to the starter, and one to everything else. The one to everything else had the fusible link in it. With everything hooked up correctly and the fusible link blown, an e36 would crank all day and do little else.