Battary light on gauges do not work Topic is solved

sam range · Post by **sam range** » 08 Nov 2004, 14:32

1988 volvo 740, battery light stays on, system is charging always start, gas gauge ,speedometer and remaining gauges bearly move. I changed fuses, clean battery terminals. any clues

LaRy · Post by **LaRy** » 09 Nov 2004, 10:16

Lock at the electrical connections at the back of the alternator. It is very common that the thin wire for the charging lamp is broken or has a bad insulation very close to the alternator. If that one is broken the lamp stays on even when it is charging, and odd things will happen. The enviroment down there at the back of the alternator is greasy, dirty and hot.
Come back to this forum if that connection is OK, and I will give you more suggestions.

sam range · Post by **sam range** » 09 Nov 2004, 12:08

I checked all the connections, even the alternator was replaced.

LaRy · Post by **LaRy** » 10 Nov 2004, 11:34

Hi, you should still check the red small wire connected to alternator D+.
The fact that the charging lamp is on at the same time as the alternator is carging is showing that something is odd. The principle for this lamp is that you get 12 volt from oppsite side of the lamp and ground through the not charging alternator, and it is on when not charging. When charging has started, you will get 12 volt + at both sides of the lamp, because now the alternator is feeding the lamp. This feeding voltage D+ will also go to a voltage stabilisator, feeding the speedometer, fuel gauge meter and rpm-meter, the voltage stabilisator is not working in your car.
What happen when you turn the ignition switch to drive position before starting the engine? As you probably know, in this step it is some sort of indication lamp test, allmost all indication lamps should be on. Are they?

sam range · Post by **sam range** » 11 Nov 2004, 08:02

Sounds like you are on the right track, when i start the car the battery light stays on, and all other gauges do not work. at night when the head lights are turned on the gauges do not move at all. I will try and look around the alternator again, but i see all the wires connected.

LaRy · Post by **LaRy** » 11 Nov 2004, 10:41

Check also the grounding for the complete instrument cluster. Loosen the panel to the right in right footweel, (the one with the fresh air intake). Aproxamitely 10 cm above the floor you will find a grounding list. One of those flat pin connections is for the grounding of the complete instrument cluster. Those flat pins are sometimes getting "tired", so the are more or less loose. Lost of ground for the voltage stabilisator will also cause problems like you are describing. The fact that the head lights have influence to the problem, is a sign of bad grounding.

You did not give any reply what happens with the alarm lamps with the ignition key in drive position without running engine. Are they all on or off?

sam range · Post by **sam range** » 12 Nov 2004, 07:02

This is what happens, i start the car and it comes as normal with the seat belt buzzer sounding. when the gas pedel is pressed and with the rpm increased the battery light comes on and stays on all the time. The gas gauge only moves a little with the tank full, the speedometer will not go past forty miles per hour. With the head lights on, the gauges go flat. The car runs fine, with no other problems, i am sure it is a ground somewhere. I should have did more research before a garage installed a new alternator at a $150.00 cost and nothing changed.