20 replies to this topic

[Jamz14]

Took the car this weekend to have the annual done and to shake it down in an HPDE 3 event. Annual went great, thank you all again, and the first two sessions went well. Little problems with the car but nothing major.

Then, just before going out for session three, couldn't start the car!! Bummer. And of course I left the FSM at home. But we did the best we could to fix, but no luck. Had some great input at the track on somethings to try. Still no luck.

So here is what is going on.

Turn the key on, but no dash lights. I know the battery is good and is fully charged. I checked the kill switch and it is good and we have power there too. BTW, also can't hear the fuel pump either. We have voltage to the main fuse block and to the alternator. The main fuse and fuel injection fuse have continuity. Thought the injection relay might be bad but we swapped it with someones known good relay and it didn't fix the issue. Checked the ignition switch continuity and it is good too.

Then I checked the white wire voltage going to the ignition switch and it measured 5 volts . This didn't seem right. I stopped there for the night.

Any ideas?

Thanks,

James

[Ron Alan]

Had the same issue after a motor swap...80amp main fuse was blown. You said continuity was good buI do you actually get voltage on the out side? If so you should have voltage to several things that aren't key related which might narrow it down to ignition? Also, does your kill switch cut power or ground? Do check all your main grounds either way.

[Jamz14]

I went out to test the main fuse as ron described this morning and I got a weird result, less than 5 volts on both sides. It was weird because both at the track and last night I measured 12 volts on the outboard side of the fuse. I checked the kill switch and 5 volts there too. Back to the battery and 10 volts across the poles. So I looked for something that I kicked or left on and I noticed the hazard switch was depressed at some point last night. I turn it off and now I am getting 12 throught the switch, both sides of the main fuse and both white wires to the ignition switch connector. But still no dash lights or working electrical for that matter.

Is it relevent that the starting system voltage drops to < 5V when an auxillary system is switched on?

J

[KentCarter]

Certainly a sign of a bad battery or bad battery connection. I'd swap a known good battery in or at least put jumper cables on. Do you have a 2 pole or 4 pole kill switch?

[Keith Novak]

I'd stay away from diagnosing anything with jumper cables on. When I put them on my car, weird things happen like the fuel pump runs with no jumper in the daig box and the radiator fan switches on so I'm sure other weird things are going on.

[Jamz14]

Kent,

Two pole switch provided by Advanced auto and installed in his preferred method. Been working great with street driving for two weeks. The battery is brand new. Already tried jumping with no luck. I don't think it is the battery as the car was starting great at the track. Driver came in after run two, then we started it right after that, then 10 minutes later went to try and drive over to another pit and all electrical seemed to be dead. We were able to bump start it once, then after that nothing. I assume nothing on the second bump start because the fuel pump and injectors weren't getting power.

Thanks,

J

[Keith Novak]

Do you have another alternator you could try? On some cars at least, fried circuits in the alt will cause any number of problems.

[Jamz14]

I don't. Can't we take it out and have an alternator test done?

Thanks Keith.

[davew]

Why don't you take a couple steps back and diagnose the problem rather than this hap hazard approach.

Start by charging the battery to a full 12 volts. Miatas do weird things at 10 volts. Even weirder at 5volts.
Then check you voltage down the line. At kill switch, at alternator. Check the grounds. Not just a look and a wiggle. Take them appart, sand the connectors and reinstall.

Work smarter, not harder.

Dave

[Jim Drago]

Amen to what Dave is saying...

[Bench Racer]

Work smarter, not harder.

Dave

Has someone been turing the "Kill Switch" to the OFF position?

[Jamz14]

Dave, Drago,

I completely agree with you. I thought my initial post demonstrated that philosophy. I started at the battery and know that the battery is good, as stated in my original post. 12volts. Went to the kill switch, next thing in line if installed per Daves instructions,and it is. Have continuity and 12 volts across as stated in first post. Then went to the alternator and the fuse box, 12 volts to the alternator and continuity through the 80 amp fuse, as stated in first post. Injection relay next, swapped it out with known good and still nothing, as stated in first post. This all seems to be sequential as per the wiring diagram

Now at this point I didn't follow the path perfectly. I am not an electrical person and relays and such are a bit intimidating to me. So I jumped to the ignition switch. I pulled the switch and have continuity as outlined in the FSM in all key positions. Then I tested the white leads to the switch as stated in posts above and initially had 12 volts. So at that point, I relooked at the FSM and saw that there were a couple of fuses under the drivers side interior that were in line. Pulled those and checked......good. I then must have hit the hazard light button last night and didn't know. Read Ron's post above about continuity through the main fuse maybe not being good enough so this morning I go out to check both sides of the main fuse box to ensure the fuse is good and I all of the sudden I got 5 volts or less on both sides!!!! This was different than what I saw last night and that caused me to find that having an electrical component on ( the hazard light switch ) was causing a draw down in current. So I turned the hazards off (they weren't actually on, just the switch on) and that caused the voltage to come back up at the switch and fuse block to a little less than 12. Thinking that the battery drained from the hazard light drawing down current all night, I put the tender on it this morning.............because I know to start with a good charge in the battery from this type of testing and problem resolution.

And silly me, not being an electrical whiz, thought that the fact that having a circuit opened, like the hazard lights, causing the voltage drop, might indicate something in particular to some of the experts here. So I was hoping that might actually short track me to a cause. However, I knew that if it didn't, I was going to have to pick up from where I left off last night at 10 pm and run down the circuit line bit by bit. But again, not an electrical whiz and electrical diagrams being a bit daunting and I am having to learn how to test and read on my own as I go, progress is slow.

Something in me tells me that the voltage draw down caused by the hazards indicates a ground issue. I was hoping to confirm that here. But, I will try my best instead to go sequentially in line as you recommend ( and as I was trying to do) and when I get to a ground in the diagram I will check those at that point.

I know you are trying to help,........and you are! I hope that some of my sarcasm isn't taken badly. It has been a very long 5 days. Thursday before the Saturday track meeting I am in Austin on business and the car isn't quite ready. That's ok, because the boy is going to do a bang up job and finish the list of things I had for him to finish so that we can get the annual on Saturday. Get back home Friday night after mid night and need to leave for the track at 5:30 am. Ooppps, the boy let me down and nothing is really finished. If you have young son's you might be able to appreciate the frustration. Finally get the stuff finished and trailer loaded and leaving town at 8:30 , 3 hours behind. Then the stress of tech in 100 degree weather at the track. Then start Sunday's HPDE 3 shake down and things going fairly well and working through our program. Then this. And if you have a young son as your driver, you can probably appreciate the frustration in having to deal with that in 103 degree weather at the track and trying to fix something that you are marginally incompetent in and get him back on track to complete our program. But nothing works. So load up at the end of the day, because I kept trying without the forgotten FSM left at home, we leave the track at 5:30. Only to drive 2 hours and get stuck sitting on the freeway for another hour because of a 3 car pile up. Ok, finally get home and guess what, the key in our tow vehicle will not come out of the ignition and is stuck in the accessory position. That leaves all the dash lights on and I know the battery will be dead in the morning and the tow vehicle happens to be the wife's car and she needs to go to work. So have to explain to her that she will need to connect battery in the morning. I don't know what your wife is like, but that doesn't go over so well with mine. Doesn't like special and new things to do to overcome problems, know what I mean? So have to try and fix that on Monday after work and still try to fix race car so that we can complete our open testing at a track the kid hasn't driven at before the May race that is for points and he needs to be competitive.

So a long story long................ I'm beat and cooked. But I will get this solved and back on program.

J

[Jim Drago]

Sorry, It sucks when this stuff starts
Jim

[Jamz14]

Dave, Drago,

Please accept my apology.

The very first thing in the wiring diagram is the battery. It goes in two directions, the positive and the ground. I followed the positive path thinking I was doing the right thing and moved sequentially down stream from there. But, before I could move on and clear the battery, I should have cleared the ground path too. Just went to garage to start a long night diagnosing.....and.........I know you have already guessed it.............main ground was loose. dash lit up immediately and car fired right up.

Again, please accept my apology. Now to bed and rest.

J.

[Bench Racer]

Now to bed and rest.

J.

Great JOB!!!

We ALL learn as we go.

[Tom Hampton]

Something in me tells me that the voltage draw down caused by the hazards indicates a ground issue. I was hoping to confirm that here. But, I will try my best instead to go sequentially in line as you recommend ( and as I was trying to do) and when I get to a ground in the diagram I will check those at that point.

So a long story long................ I'm beat and cooked. But I will get this solved and back on program.

J

J.

For not being an electrical "wiz" that's a well informed thought. I know a few EEs that wouldn't make that leap so soon. Nice job finding it and fixing it.

Also, nice overall response, and apology.

[davew]

No apology required. Some times it is easier to take a step backwards and start over again. I wasted 1/2 a day a couple weeks ago because I did not step back and think about the basics.

One comment. In your original post you stated "couldn't start the car!! ". But you never said what the car would or would not do. From reading the entire thread I understand it would not crank. That would eliminate everything except starter, battery and associated wires and switches. I would never have looked at a fuel injection fuse. So that lack of accurate info sent well meaning people on this site, into wild goose chases about alternators etc.

Concise info (it does not crank or it cranks but has no spark) will allow the smart people on this site to diagnose the problem quickly.

Apology accepted, but not needed.
Glad the car runs
Dave

[Jamz14]

Thanks all, after a good nights rest, I am feeling like my more cheerful self again.

[Jim Drago]

Dave, Drago,

Please accept my apology.

The very first thing in the wiring diagram is the battery. It goes in two directions, the positive and the ground. I followed the positive path thinking I was doing the right thing and moved sequentially down stream from there. But, before I could move on and clear the battery, I should have cleared the ground path too. Just went to garage to start a long night diagnosing.....and.........I know you have already guessed it.............main ground was loose. dash lit up immediately and car fired right up.

Again, please accept my apology. Now to bed and rest.

J.

Great news... no apology needed... I know speaking for myself.. grounds have kicked my ass before as well, usually once they get you once, they rarely get you again... That is the good news

[davew]

Meathead bought Brian and I a VERY large steak dinner after finding a ground issue that had been eluding him for 3 months.

Don't feel bad

Dave