1990 Volvo 240 DL Charging System Problem

[billofdurham]

Thank you for the update.

Bill.

[Volvofix1]

After reading the conversations I would tell you to grab the alt. fan pulley and see if it slips ,the alt. belts may be worn and pushing with a finger may not show a problem.If the alt. belts are glazed tightning will not help,youneed at least 13 volts to charge the battery,has the battery been load tested at a car parts store? A big problem many 240's have is that the drivers door lock motor can stick and draw down the battery disconect the door lock solenoid for a few days. As far asthe shift position problem look at the little bushings at the shift linkage they go bad often. Are your motor mounts OK? they can screw up the shift position.

Dick K. from FLA ...aka volvofix1

[Volvo 240 Newbie]

On the D+ I have a car that has 1.36v at D+ terminal. IF I jumper to bat I get 13.65 at Battery.

Ive traced the D+ red wire to gray connector which turns to yellow wire going into firewall. Where does this terminate or does somebody have a copy of diagram for 1990 240DL?
Thanks

[billofdurham]

Welcome to Matthew's Volvo Site.

The wire from D+ goes to the charging lamp in the instrument cluster. System wiring diagram attached shows the wire to be red all the way but colours do get changed at times.

240 1990 charging circuit.pdf

(147.23 KiB) Downloaded 736 times

Bill.

[lummert]

Is the battery lamp on the instrument panel working properly? Does it come on when you turn the ignition switch to the on position? IIRC, if the bulb is burned out the alternator will not charge the battery.

[billofdurham]

+1. A valid point.

Bill.

[Volvo 240 Newbie]

OK, I changed D+ to a red switched wire not knowing the series through the lamp indicator. THanks for the info. I'll fix that.

Well I thought I had it fixed as when I got power to D+ it began to charge and working fine till 3 days later when daughter called and batt was dead. 12.25 on D+ and 12.34 on output of alt.

New alternator, new belts,checked the ground to alt no luck does not seem to be charging.

Also does anyone know how to bypass the automatic headlight feature? would rather have the option to turn on rather than pulling fuse when trying to get crippled car home:)

Thanks

[Retired MVS Contributor]

Battery charging does NOT rely on the filament in a light bulb...30 amps could be on that wire if the battery is run down and that wire would COOK!...

When the igintion is switched on but the engine is not started, 12 volts from the ignition switch passes through the bulb, through the field of the alternator, then to ground, and the bulb lights...When the engine is started the alternator puts out 12 volts IN THE OPPOSITE DIRECTION on this wire, bucking the ignition switch voltage...With two positive voltages arriving at the bulb from opposite directions, the two voltages cancel each other and the bulb goes out...If the alternator stops putting out while the engine is running, or if the engine stalls, the bulb will light with the voltage to it coming from the ignition switch...A dimly lit bulb while the engine is running is an indication that the system is over-charging...

A possible cause of your problem is a short between the two wires in a sleeve coming off the alternator, running back to the firewall and into the engine connector on the firewall...One of these wires is the D and the other is the oil pressure switch wire...With age the insulation on these two wires dries out, the insulation falls off, and the two wires short to each other...The short will be back inside the sleeve right next to the alternator but will not be visible because it is inside the sleeve...

Jerry

[Volvo 240 Newbie]

I checked the wiring for that reason first. Went through the grounds and it seems to be working now, but that scares me more since it's acting like a germlin moving around.

Guess I will find out in a few days if it's charging.

Thanks
Everyone

[Retired MVS Contributor]

The D+ wire is for the alternator indicator lamp only...The alternator will work with it disconnected...It has no other function and if that bulb burns out, everything else will continue to function normally...It is a waste of time to check fuses when dealing with starters and alternators...Modern alternators are capable of 100 amps or more, and the momentary surge current when the starter is engaged can exceed 500 amps...No fuse can handle that and both alternators and starters are connected DIRECTLY to the battery by heavy wiring...The alternator draws it's excitation voltage from the heavy red cable connected to it's B terminal...

The 240's transmission is hydraulic and does not rely on the battery or the alternator...As long as the engine is running it will work, relying on engine RPM, drive shaft speed, and throttle position...