Car Dies When Jumper Cables are Removed from Battery

[gtd65]

Hi Folks,
Our car has been standing for a while due to a cracked gas tank.

The battery was flat, so I decided to jump the car and after a couple of cranks it fired up fine but I noticed a couple of things that were unusual:

1. The headlights were on but the switch was on the off position (before cranking)
2. The clock display was illuminated but the time was not showing.
3. When I removed the jumper cables the engine died.

I'm assuming that this has something to do with the alternator but points 1 and 2 have me somewhat confused?

Any ideas?

Cheers in advance

[compactfean]

Id start with the alternator and diagnose the other issues after it can stand on its own 2 feet.

[gtd65]

I've been reading posts about 75A fuses - does this apply to the S14?

[180sx91]

Sounds like the altenator

[compactfean]

I've been reading posts about 75A fuses - does this apply to the S14?

Yes, the wiring for the alternator goes alternator, fuse, battery.

[gtd65]

Got the alternator checked at Advance Auto Parts and all is well with it...

Interior electrical problem remains....

[jbracy7]

Check Your grounds for rips or tears, metal to metal contact can cause those problems

[AZhitman]

Alternator fuse.

If your alternator is good, you're not getting power from the alternator to the ECU.

[gtd65]

Alternator fuse.

If your alternator is good, you're not getting power from the alternator to the ECU.

Would the alternator fuse (is this the 75A fuse?) cause the interior electrics not to function?

e.g. power windows, dome light, dash cluster lights etc.?

Thing is I got a spare 75A fuse at the wreckers yard and it made no difference - has to be something common that's being overlooked here..?

[gtd65]

Check Your grounds for rips or tears, metal to metal contact can cause those problems

Everything looks good with the grounds and I cleaned up the connectors for the alternator and the ground near the strut top/battery area. No change.

Also now got gas tank changed for a good one, one problem solved - electrics to follow hopefully!

[compactfean]

Power windows, dome light, etc, is on another fuse, and could be a separate issue. Have you checked continuity from the alternator plug to the battery? or from the alternator plug to the 75amp alternator fuse? checked resistance in the alternator fuse itself? If all is good than alternator or ground is your issue (ground is pretty obvious, battery - straight to chassis)

[gtd65]

I'll get a check done on the grounding (I'm out of state right now) but as the car cranks over and starts fine I'm assuming that the battery ground has to be OK?

All of these problems appeared at once, after I disconnected the wiring to the gas tank...or at least there wasn't any problem with the car until I decided to do that....

Is the dome light fuse/circuit in any way connected to the grounding of the alternator?

[gtd65]

Just been surfing around and found this snippet:

If:
None of your gauges, accessories and dash lights work then its the alt fuse.
or
If none your dash lights and rear lights work then its the rear lights fuse.

[Rays240sx]

i had a similar issue, it ended up being my 75A fuse

[gtd65]

i had a similar issue, it ended up being my 75A fuse

So your car wasn't the SE version?

Ive read now that in the SE you need to check the 100A fuse?

I'm really hoping it's that simple!

[Mercury_Hg]

Ive read now that in the SE you need to check the 100A fuse?

Yup.

[gtd65]

YUP - 100A fuse is blown - need a replacement!