Volvo 290 not charging, seems like it want's to because the drive belt is chirping and squealing, alternator bench tests good, batteries new, physically followed wiring harness through the deepest and darkest places and checked every plug that I found. slow blow fuses good, diodes in battery box meter 5-7 ohms one way OL the other way, cleaned and re attached every ground cable, I metered the alternator with engine running and battery voltage at 25 volts, B+ reads 25 volts, D+ also reads 25 volts, W terminal reads 12.5 volts, I also tested the W circuit it is connected to the hour meter and charge lamp it seems OK but light doesn't come on until battery voltage is below 24 volts. Tried running with hour meter disconnected and buzzers and warning lamps came on. The D+ wire meters good between the alternator and the safety switch in the battery box, With the key on I only had power to one large red wire on the safety switch none of the 4 small wires had power, My hunch is that something is not letting D+ excite the alternator, I even went as far as disconnecting the alternator with the engine running and reconnecting it to some batteries in the back of my pick up and the output Voltage was 28 volts and the drive belt stopped chirping and squealing. Has anyone seen anything like this before? Many Thanks Ike
The D+ and W terminals, along with the diodes in the battery box lost me, not familiar with volvo's way of doing things, but that never stopped me before... Did you start with fully charged batteries that are holding their charge? Is the belt tight? Does the voltage hold with the key on but the engine not running? (any chance there's some short or big amp draw causing the squealing). It sounds like you investigated this pretty thoroughly. Did you check the voltage drop from alternator to batteries, alternator ground to frame/engine ground? You could try using the alternate batteries to help diagnose this, use the same wiring to hook up to the excavator batteries the same way the spare batteries were hooked up and then move one thing at a time until the problem comes back. Voltage regulators can fail when they get hot, and then work fine when they cool off, causing it to work on the bench, but not after it's run on the machine for a bit. That wouldn't explain the chirping or it working with the other batteries?
Thanks for your reply Delmer The D+ means dynamo its European for stator I believe and the W represents warning, The alternator when tested on the bench has good output without the stator terminal connected, in the machine unfortunatly it wont excite with the stator wire connected and wont run with it disconnected, iv'e tried other batteries, load tested all good, Thank again Ike
Had this on 2 volvos.Was the relay for preheater screen in the air intake(glowplug basically)was failed and constant power was going to it and drawing down system.Replaced batteries and alternator to no avail.The relay is a large one in the back of the battery box with quarter inch size positve running to it.Just disconnected them and have been fine since.
Thanks Delmer and Skadill, I finally figured this out, One bolt was broken off the fuel pump bracket causing the lower belt to slip, 6 hr job to drill it out, also bearing was shot in fuel pump, OEM part costs $1050,00 from Volvo WOW was able to repair for $56.00 talk about highway robbery, now with the bottem belt tight and the flimsy little single 3/8 upper belt tight the charging system is working fine, they really dropped the ball on this design!! the alternator belt tension system is the same technology as 1975 Ford pickup pry-bar and bolt? a machine of this size with 2-8d batteries , AC lots of lights should at least have 2-1/2" belts with some sort of threaded rod for adjustment I'm not a hater I'm just sayin... thanks again for your response Ike out