[gbcaddy]

Hi Guys
I really would appreciate some help on this one, i have a 2000 STS which i have had for roundabout 2 years now and a better car i will never own, she has never ever let me down except for today, please let me explain.
Driving along the motorway about 60mph she suddenly started losing power, even when i tried to accelerate she got slower and slower and started riding rough, to the point where the engine died altogether, i pulled her over and let her rest for a few minutes, out of interest i scrolled through the D.I.C only to see that the battery voltage had dropped down to around 10 volts. After a further few minutes i re- started the car (leaving the D.I.C on the battery voltage mode) and she ticked over perfectly with the voltage showing a healthy 14.1 volts, however, a further 2 miles down the road the voltage suddenly started dropping ,again she got slower, and again she cut out, this happened 4 times altogether to the point where i left her for a full 30 minutes.
Again i turned the engine over but this time remained stationary,again she ticked over nicely and showed a healthy 14 volts but within 2 minutes the voltage agained dropped drastically and the car started misfiring badly to the point where,again, she cut out altogether. I called recovery services and explained the symptoms, within an hour the guy came and tightened the connections to the battery(POSITIVE BEING SLIGHTLY LOOSE) and said "she will be fine now", .While he was still with me i again started her up, again she ran great for a couple of minutes, then again the volts dropped drastically, again she misfired badly ,and again she cut out. He then explained that it was either the alternator or that there was a short circuit somewhere which was draining the power from the battery so quickly,his suggestion being to call out an auto electrician as he didn,t carry the relevant diagnostic equipment.
Before i start spending big money on these guys is there something i should be looking for.
Again guys any help is very much appreciated.

Kind regards

GB CADDY (Steve)

 

[Submariner409]

Great Britain - Long Live The Queen !!!!

Your symptoms indicate either a dying battery - dead cell - or a serious fault with the internal voltage regulator in the alternator.

First off, how old is the battery ? Any more than 6 years and that's the prime suspect.

Now, remove the rear seat pad - lift forcibly and tilt up -(unplug the heated seat pigtail on the passenger side) and check the battery terminal connectors as well as the ground (earth) cable at the body floor.

Given the slowly lowering voltage (time rate compared to a complete disconnect) the problem may involve the alternator - voltage regulator section. Not fun to remove. But a local electrical shop should be able to overhaul it.

Go up to the sticky posts ^^^ at the top of this forums page. Open the post "How to pull codes". Use the tutorial to operate your car's built-in diagnostic code scanner: practice, write down any codes found and whether they are Current or History, then return to the post to open the address link with "obd2" in it. That will take you to a Master Index box of all trouble codes and their definitions. Codes are P (Powertrain), B (Body), C (Chassis), and U (voltage and serial data).

 

[gbcaddy]

Thank you Sub i shall do that
(BTW the battery is less than 3 months old)

 

[Submariner409]

Thank you Sub i shall do that
(BTW the battery is less than 3 months old)

Hmmmmmmm............This looks more like alternator/wiring harness faults.

Pull the codes - the car is very good at crying "Help !".

 

[Ranger]

Don't rule out the battery just because it is only 3 years old. I've had them fail in less than a year and have had 2 fail right off the shelf.

 

[gbcaddy]

Hi all

Pulled the codes and have two current;

C0625 LEFT REAR POSITION SENSOR MALFUNCTION
B1390 DEVICE VOLTAGE REFERENCE INPUT CIRCUIT MALFUNCTION

Any advice as to my next course of action would, as always, be much appreciated.

Regards