Just got eveything else sorted out and now I've got another problem

The battery warning lamp on the Drivers Information Centre illuminated on the way home and the ammeter was showing no charge. Got home switched off and tried to restart, flat battery. Obviously a dead short somewhere. Checked it with the scanner which shows a Code 46.
Anyone else had similar problems that could save me months of searching?

 

What year??? Chances are the alternator quit working and you drained the battery getting home. Aside from following the trouble shooting chart in your FSM for a code 46, I would fully charge the battery, if it will still take a charge, and check the alternator output. You may not have a short after all. If you do, you'll have to trouble shoot to track it down.

RACE ON!!!

 

Sorry, it's a 91 with a L98

 

The battery symbol light on the DIC tells you that the alternator output voltage is below 13 volts (not charging), or over 16.5 volts (overcharging). Also, C4's do not have an ammeter, the meter on your dash is a voltmeter and if you saw low voltage, then your alternator is defective or the fusible link in its output wire is open circuit. You do not have a short circuit in your electrical system because only one circuit does not have a fuse or a circuit breaker, and that is the starter motor. Any short will burn out a fuse or trip a circuit breaker. You likely have a discharged battery and you should charge it up with a battery charger. The alternator was not intended to charge up dead batteries and doing so will shorten the life of the alternator.
You can tell the state of charge in your battery by measuring the battery voltage. The dash voltmeter reads low if the engine is not running, so use a separate voltmeter. 12.0 volts and below, discharged, 12.9 volts and above, fully charged and linear in between.
Code 46 is set when VATS detects an incorrect key, that is, doesn't see the correct pellet in the ign key and then the ECM will not allow a crank or pulse the injectors. I have typed a procedure to diagnose VATS over 300 times, so if you use the forum search function, you will find my diagnosis for VATS problems. Let us know if you need further help.

 

Sorry my mistake, it should read voltmeter.

The battery was new about two months ago When out for a run today, stopped for five minutes, started up again no problem and arrived back home about 5 mile and the battery symbol was lit., the voltmeter was almost at the bottom of the reading ( I can't remember what the lowest number is) and when the engine was revved there was no movement at all on the voltmeter.

I used a scanner and it returned a code 46 and named the anti theft system, yet the car started OK after a short charge but there was still no charging.

You couldn't point out where the fusible link is could you, the car is a 91 with a L98 engine.

Thanks

 

There are 2 fusible links on the alternator wires. One is on the output wire from the alt to the battery. Use an ohmeter from the batt + terminal to the alt output terminal, it should read the same as touching the ohmeter probes together. The second fusible link is on the red wire on the alt connector. Unplug the connector and use the ohmeter from batt + to the red wire, it too should read essentially 0 ohms.

 

Thanks for all the input.

Checked everything and it all points to the alternator. There is no increase of voltage coming out of the alternator at any speed, it reads the same as the battery.

So, change the alternator.

Next question (the last I hope), Is the 91 model alternator specific to that year or do other year models use the same.

Thanks again

 

I just installed an Autolite pro-tech rebulit one, #CL 7356256. $100.00 with lifetime warrentee and 24 month road service should it go bad, from Shucks Auto. Do not know what they call themselfs on the right coast.

Ten minuets to remove, 3 hours to find one , 15 to put back on.

works great.

see ya on the road

tom

 

Thanks everyone. apparently I accidently fried the alternator when using a boost starter. Learnt the hard/expensive way.

Thanks again