Hi,

740 230FT with Bosch ignition system. Battery loses charge overnight and engine will not start. Starter turns over but not enough charge to get the engine running. When battery is charged fresh from battery charger it starts well. The battery is 2-3 years old and has been rarley used over the last year. This battery drain problem was first diagnosed about 18 months ago and since then the car has been rarley used.

I have looked through the forum and I have got a lot of tips and tried things but I still can't get the battery to hold charge over night.

I have cleaned battery and engine block connections +ve and -ve.

It feels like I have a drain of power with something left turned on or a short circuit.

I tested for drain with engine not running and pulling fuses. I got a 0.15 drain on fuse 5 the instrument panel and clock. And a similar drain on fuse 1 the fuel pump.

Are these drains normal? I figure the clock must use something.

The alternator and battery test have both tested good when running. The alternator is sending good power to the battery. (Of course the battery reads low voltage when it is drained.)

I have seen that there are sensors and relays that can cause a no start. The fuel pressure regulator, fuel pump relay, power stage amplifier, fuel injection relay, radio noise suppression relay, RPM sensor.

But my 740 starts right up with a fully charged battery.

Could it be the battery not holding charge? I have avoided buying a new battery so far. Is there a way I can test if the battery holds charge?

I have looked at all the small lamps in the trunk, under hood and they all seem to be off and not draining when the car is inactive.

Help appreciated!

Thanks,

Dean

You basically have two cables going to the pos terminal on the battery. One's for the starter circuit and the other is for everything else. Maybe try disconnecting them both and touching them to the pos terminal one at a time. If either one sparks much then there's a short with that cable system. The starter is pretty simple but if it's the accessory cable then you're going to have to start pulling fuses to find out what's wrong.

I can also add to the battery drain problem on my 740 that the problem is intermittent.

I tested the battery before starting this morning and it read 15.5v. And the engine started straight up.

Dean

Check out this page on how to test your battery,

http://www.repairfaq.org/ELE/F_Car_Battery.html

Alot of auto parts stores will check you battery to see if it will hold a charge. Maybe try it yourself by charging the battery once more and leaving it disconnected overnight. If it still looses charge without being connected then you need a new one. If it doesn't then you've got an electrical problem somewhere. If you have a sedan open up the trunk inside access panel to see if the light is still on when it's closed.

I got a new battery. Seemed I had to eliminate this possibility. The original was three years old.

I have not left the car over night yet. But I feel I still have the problem.

The volt meter on the instrument panel reads about 12v which is what the old battery read.

The car started with the new battery but it was not a very powerful start.

I feel like I am not getting the full current from the battery into the ignition/electrical system.

I have tried using a wire from the battery positive direct to the starter and this did not change anything.

Sometimes when the car starts, it runs very low, maybe no idle. I have to keep my foot on the pedal to keep the revs up. Then other times, probably when warm, it idles fine. Might be related.

Could it be the ICU failing or the power stage amplifier?

Car runs excellent when moving along.

Any more ideas?

Thanks,

DP

Before you start blaming computers, sensors, etc. Check all your battery cables. They may look good, but corrusion. The idle, is more than likely has nothing to do with your battery. Dirty throttle body, ICV, plugs, wires, distro cap/rotor. Stick with the basics. voltmeter on the panel, unreliable.
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Post Back. That's whats makes this forum work.

With the new battery I got a complete fail after a day. The starter still turns, and I tried a jump start but this time it would not start the engine.

The starter keeps turning and the battery is not dead it reads good. I always thought this was a battery problem as whenever the engine would not start if I charged the battery it went. At least a couple of times. But this time no good.

(I wonder if removing the battery reset some electrical component and and got it starting next time the battery was connected.)

Anyhow I have come to think it is fuel or ignition problem. Probably fuel. During the last jump start attempt we had plenty of current and plenty of turning the starter but no start. And it seems no fuel, at least I could not smell any and with alot of pumping I thought I would smell fuel. I do hear what I think is the fuel pump as soon as the key goes to the number two position.

Car is otherwise well maintained, clean engine. Plugs, distributor and rotor two years old. Coil looks old.

Thanks for the help and keep the ideas coming.

DP

The problem turned out to be the radio suppression relay on the fire wall. What I can't figure is why using a jumper got it going so many times. Lead me to think it was electrical. But in the end the jumper did not work. Seems like maybe just the extra current with a jumper start or a freshly charged battery got the faulty relay to work.

We found it by tapping the relay itself while trying to start the car. It coughed and spluttered.

New relay. No problem.

Truly enjoying driving my first Volvo.

DP