cavalier diesel - paulc924
Help needed please. Earlier in the week my son's Cavalier made a strange whirring noise when the ignition was turned on but he was still able to start the car when he couldn't identify the noise. He stopped the engine and turned off the ignition to try and see what was wrong. This whirring noise continued for several minutes and when it stopped he tried again. The ignition as turned on and the whirring noise began again. It was coming from the back of the engine. This time the car would not turn over and it was left parked up. Suspecting a starter motor problem I disconnected the +ve lead from the starter and jump started the car so we could bring it home. We got the starter off but could't get the solenoid to operate using leads from a battery. A starter was sourced at a local yard and prior to putting it on the car I tried to test it. I couldnt get the solenoid to operate. I then noticed a small metal tag from one of the starter terminals into the solenoid. This suggested to me that the small wire to the tab on the solenoid was negatively switched. I checked the small wire (that energises the solenoid) to earth and found it was open circuit which closed when the key was switched to the start position. The new solenoid was checked by applying negative to the small terminal and everything seemed o.k. The starter was fitted and the car has been used for a day or so. Yesterday the car failed to start and now when the ignition is turned on the dash lights are dim and a buzzing noise comes from behind the light switch. When the buzzing stops after a few seconds the dash lights become bright again but the engine will not spin over, nor can you hear the solenoid click when an attempt to start is made. I have checked the signal to the solenoid again and yes it is a switched earth. I have not come across this before. Sorry to be so long winded but he loves his car and needs it for work. Thank you and regards, Paul.
cavalier diesel - asti
As far as i know the feed to the small terminal is always battery voltage and not earth. The electrical switch on the back of the ignition switch on vauxhalls of that age are prone to failure. I am sure someone will correct me if i am wrong.
cavalier diesel - elekie&a/c doctor
I'm afraid none of this makes much sense.The crank/signal feed wire to the solenoid is definitely a positive supply (usually a black/red or black/yellow on Vauxhalls).I am not sure why you have disconnected the battery lead to the starter to jump start the car.I would suggest that the battery may be low voltage (possible charging fault) ,worn ignition switch contacts or poor engine earh circuit to battery.hth
cavalier diesel - Number_Cruncher
Please don't take this the wrong way - but I think the best way for you to avoid your Cav becoming an electrical fire would be to take it to an independent auto-electrician.

Number_Cruncher
cavalier diesel - DP
I agree with Number_Cruncher.

My old mk2 Cavalier had had an immobiliser installed (badly) and the switched live feed to it had been spliced into the fuel pump feed at the fusebox. Trouble is, not only had the muppet done it on the battery side of the fuse rather than the pump side, he hadn't fitted an in-line fuse either.

The wire came off the immobiliser, bounced around behind the dash for a bit, and then eventually shorted against one of the dash mounting brackets. It was only the pump relay popping and cutting the feed that stopped the whole lot going up - I will never forget the smell and the sight of thick acrid white smoke pouring through the face vents.

If you're not sure, get it looked at by a pro. Treat car electrics like home electrics.

Cheers
DP
cavalier diesel - Screwloose
Paul

The earth strap on the gearbox used to be a common fault on various FWD Vauxhalls. The connexion between the solenoid winding and the motor-feed bolt terminal is probably for the pull-in coil.

Starter solenoids contain two electro-magnet circuits; the [larger] pull-in coil is earthed through the motor brushes and that earth is lost once the solenoid contactors switch the motor feed on. The smaller winding [the hold-in coil] is earthed through the starter casing and remains energised all the time the starter excitation feed exists.
cavalier diesel - paulc924
Thank you to all for your replies. Before I posted the request for help I had had the battery tested and it proved o.k. at our local supplier. Following your replies the car would be o.k. one minute and then not start the next while this buzzing was going on. I called in an auto electrician who confirmed that the buzzing was down to the heater plug relay and suggested there wasn'y ebnough life in the battery. A new battery was purchased and the car has been right as rain ever since. Looks as though there was an intermittant battery fault. Best regards, Paul.
 

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