Super Happy Electrical Gremlin! Update: Defeated!

[011]

Well, now that I've got your attention with that Super title, here's my problem that I'm hoping someone might be able to shed their wisdom upon.

Car is a supercharged AW11 MR2. We initially thought that the car had an alternator problem, as I've heard when alternators play up they can cause strange things. But now I'm not so sure, so I just want to clarify or hear out any suggestions.

The car was acting 100 percent fine and after sitting for 10 days, it suddenly had this gremlin. It's all normal electrically (dash lights, etc) until you crank it, in which sometimes it will start normally and sometimes when you twist the key to start it will die as if someone has disconnected the battery, with no crank at all. The best example is that when the engine does start and is idling, the tacho is acting a little strange (flickering up and down about 500rpm but with a normal, flat idle speed) and all the lights on the dash are sort of half-lit but she seems to be idling okay. Turn the head lights on and she immediately stalls as if someone has disconnected the battery: No dash lights, no clock, nothin. The lights don't even retract fully.

Sound like an alternator problem? Muchos gracious to those who can offer help! Thankyou!

[Draven]

yep, sounds like the alt isn't providing enough charge to keep the spark plugs sparking and run the headlights.

[Cuzzo]

If it isnt the alternator, im thinking its really dirty terminals or a bad earth from the battery to the body/chassis. Check out the connections from the alt to the battery too.

Maybe get a multimeter on the battery and get some to make the car stall.

[CrUZida]

Doesn't sound like alternator.

If the alternator was bad, and it stalled from turning on the lights, then you wouldn't be able to restart the car without a jump.

I'd agree with the above, bad connection somewhere.

[stradlater]

Yeah, I'd say bad connection. Something has suddenly given you a bad earth.

Don't suppose you've got rats and one has eaten through a line?

[011]

CrUZida, the battery wasn't and presently isn't flat yet, though. Could it simply restart based on the 'juice' still left in the battery? The volts in the battery dropped with every restart. I would imagine, if the alt is really f-ed, you would eventually exhaust the remaining charge in the battery until you could crank over the car no more. Does this sound right?

stradlater, rats are super rare where I am (not echidnas, though - another story), but I will check and clean the battery terminals (even though, from memory, they are fairly clean) and where the battery earths in the engine bay.

Cuzzo, draven, thanks for your replies and help! Comments are duly noted.

[CrUZida]

It takes a lot more power to start a car than to run it.

If it has died from a flat battery (ie, alternator not providing charge, battery went flat), then you'd have no chance of starting it without jumping.

Remove both terminals, clean them up, clamp them back on good and tight, make sure all connections are good.
Check all the fuses.

Restart the car, get a multimeter, and start checking voltages.

[011]

No worries. Thankfully, got a good multimeter, too.

Anybody else have any suggestions? I'm all ears.

Cheers again, CrUZida.

[river]

Hi,

Logic units concur, with regards to a bad connection of earth. If the car can be restarted after the engine dies when you put on the headlights, then I'd assume the battery is being charged properly. So, this means the problem is outside of the charging circuit.

For starters, clean-up and check your battery posts, though I doubt the problem will be there if the battery is being charged okay. But it doesn't hurt to make sure the posts/clamps are clean and are making good contact.

Next thing is to check the earth straps that are bolted to the engine and chassis.

Next thing is to check the wires going into your main fuse box(es).

Have you tried your radio when the engine is running? Switch it to AM and see if you get a lot of engine noise and other crap when the motor is running. You'll hear the whine of the alternator and or engine coming through the speakers if there's some bad electrical interference when the engine is running them you also better check your ignition system, it's capacitors and all voltage (and earth) points for the ignition. If there's no noise, then the issue is not your alternator and not your ignition.

seeyuzz
river

[011]

Alright, just been down to the car. Jumped in, the interior light was on, no keys in the barrell - turned the parkers on - everything OK. Turned the headlights on and BAP! Instrument lights out, clock out, interior light out: She's deader than badger roadkill.

Seeing that it was now 'dead' and I couldn't start it, I grabbed my jump starter (these things are awesome) and clamped it up and the interior light came back on, etc. Did the headlight trick again and ZAM! She's badger roadkill again.

Took the jumper off and stood around stroking the non-existant elderly-Chinaman beard (shh, it'll grow one day) and YAZ! The interior light pops back on because the door was open. Jump in, crank it over without any problems (just a TINY bit slower when cranking) and,

a) battery is at normal voltage which seems to counter-suggest the alternator theory;
b) all the warning lights on the dash are sort of half on, including the SC light but after a peak, the SC is not engaged; and
c) I put her onto AM radio and yes, there was a shitload of noise coming through, verified by a slight rev in which the radio screamed back at me with a corresponding volume.

Rather than twisting the key to turn her off, I used the headlights. Dead badger all over again. But does any of this now help?

Thanks again all! I have been spreading the love around, even though my 'love' may not be worth much, it's the least I can do.

[BradW]

Have you cleaned and tightened the battery terminals?

[river]

Hi,

Get a jumper lead, clamp it to the -ve post of the battery and clamp the other end some where on the engine. This will give an extra earth to the car. When clamping on the engine make sure it's somewehere on the head or block - and away from fans and other things. We don't want it falling off and causing some damage. When connected, try it again.

If it seems okay, then this implies, as already mentioned by others, a bad earth somewhere.

Also, before you do the above, check the battery posts and where the earth straps connect to the engine/chassis and see if they're warm or hot. If so, this implies a bad connection and needs to be cleaned and re-attached.

seeyuzz
river

[011]

BradW, yeah they're clean.

river, thanks for your help again. I'll have to give this a try tomorrow arvo and bump this thread back up with the results. For the moment, however, it's time to put head to pillow.

[BradW]

BradW, yeah they're clean.

Are they tight. I find the best way to make sure you have a good connection with battery terminals is to remove the terminal and loosen the nut right off. Spread the terminal open as far as you can (I normally use a pair of terminal spreaders or a big flat blade screwdriver for this). Refit the terminal pushing it down as far as it will go, and tighten the nut.

I have gone out to so many cars that wont start, where the owner has been trying to fix it for days, only to find that the battery terminals are just pushed on to the battery and twisted down. Then you have to give them a bill for a service call and labour to tighten up their battery terminals .

Get a mate to get the car to play up and watch the battery terminals and earth points while they do it. You will normally hear a cracking sound and may see a spark or smoke from the bad connection.

Good luck with it.

[011]

Thanks Brad, I'll add this to the 'to do list'. Cheers and thanks for your help.