| Author | Message | ||
     John Mann Yet to post message Username: ohjohnny Post Number: 1 Registered: 5-2010 |
Hello all, After allowing my Bentley T SBX 2442 to stand for about two years, I installed a new battery and, upon turning on the ignition found that there was no electrical power to anything; no horn, no gauges, nothing. A cursory look at the fuse box found nothing blown and pressing the red button on the transmission breaker made no difference. I don't know where to begin, but the ground connection from the battery is sound and not corroded. I've searched the archives, but there are too many posts with the keyword 'fuse'. Please tell me that there is a button somewhere that I can push an the electrics will be restored... | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 657 Registered: 6-2006 |
Hi John, Did you try the main reset & cure all faults button next to the speedometer? Opps - sorry - only teasing - that button is only accessible in your dreams! Are you getting lights etc coming on? Non ignition items? oil warning light? Is it the correct battery? positive terminal to the front of the car? Is the earth lead bolted down with the butterfly nut? | ||
| John Mann New User Username: ohjohnny Post Number: 2 Registered: 5-2010 |
Umm, ahem, it has come to light that the battery was installed backwards at first and the terminals reversed. The error was discovered when it became apparent that the positive battery post was too big to fit the negative cable clamp. The two cables were, evidently, connected incorrectly several times while the person attempted to force the clamp on. They were correctly connected before I put the key in the ignition, though the damage was apparently already done before the key was inserted. Is there any hope? | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 658 Registered: 6-2006 |
John, Yikes. Basic mistake there  Yours is a very early car so I'm casting my mind back now. There is a Shunt resistor for the ammeter. This can blow when the battery is connected up backwards. This would be the first thing I would check. The alternator (if fitted) may also be damaged, You can bridge the shunt to check out everything else, but it will need to be replaced if teh ammeter is to work. | ||
| John Mann New User Username: ohjohnny Post Number: 3 Registered: 5-2010 |
Yikes is right. And yes, an early model but well maintained. Thank you for the info about the shunt resistor. I'll try to see if I can locate the resistor you mention. But even if the ammeter was out of the system wouldn't there still be something that worked? Would the diodes in the alternator still be vulnerable even with the ignition switch off? But, there is absolutely no electrical power anywhere, no lights or anything. By the way, there is no wing nut on the negative battery cable; it is merely bolted to the chassis sheet metal just aft of the battery box. I'll report back when I've checked the ammeter. Thanks again for the help, here in California, even the wheel alignment shop shook their heads and kept their hands well in their pockets rather than attempting any adjustments to the old girl. Next consideration: If the problem proves to be protracted, I will have to find a way to push the car in order to move it. Without electrics, how could the transmission be shifted out of Park? | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1275 Registered: 4-2003 |
John/ I think your car being as anciaent as it is will have the get you home lever to operate the transmission. Anyway how to get over the problem of moving a car locked in 'Park' is fairly well covered I think in those ancient writings known as Tee One Topics copies of every one being available on our technical library rrtechnical.info The last isuue (91)has all the detail. | ||
| John Mann New User Username: ohjohnny Post Number: 4 Registered: 5-2010 |
Thank you both very much indeed. The Get You Home lever will solve the immediate problem. Ingenious. The shunt resistor has been located. Now my helper will have some fun trying to dismount it without removing the dash. | ||
| John Kilkenny Prolific User Username: john_kilkenny Post Number: 105 Registered: 6-2005 |
John, For your car I don't believe that momentarily connecting the battery the wrong way round will do any lasting damage, particularly if you don't switch on the ignition. First check a circuit that doesn't go through the main switch, e.g. do the windows work ? Before you start pulling out the shunt resistor use a voltmeter to check the voltage to frame earth on both ends of it. If they are both 12 volts the resistor is probably OK. If they are zero the first thing to do is to check that your new battery is OK, then check the battery earth connection and the positive wiring up to the shunt. There is probably a simple fix. | ||
| John Mann New User Username: ohjohnny Post Number: 5 Registered: 5-2010 |
Here's how the story turned out. There is no longer a problem and I am relieved to say that there was no damage to any systems. That happy outcome can be completely attributed to my blind luck. Ahem. The battery was brand new but turned out not to have as much as a single volt of charge. That unusual fact saved me from who knows what grief. I charged it for a couple of days but it never came up to full specific gravity so I returned it and got another. When correctly installed with the terminals firmly tightened onto the correct respective cables, everything suddenly worked! The fuel pump clicked for a bit and then stopped and I couldn't help myself from turning the key. After perhaps 10 seconds of cranking, she started up and ran! It's been two years since I last took her out for a spin. The brakes pumped up very quickly and the lights went out. I promised her an oil change and a thorough cleaning. I'm sorry to have pulled the red alarm handle, but thanks for the helpful response. | ||
| Chris Browne Experienced User Username: chrisb Post Number: 26 Registered: 2-2010 |
Hi John, That is good news but two years is a long time to stand one of these cars. I would be VERY wary about "taking her out for a spin" until you have thoroughly checked the hydraulics. The brake systems and self levelling do not take kindly to lack of use. You say the brakes pumped up quickly but be wary that they may stick on due to lack of use. When were the flexible hoses last changed? How old is the hydraulic fluid? I don't want to dampen your enthusiasm in having breathed some life back into it but don't take any risks with it. There are numerous horror stories of our cars having stood for years and then someone puts on a new battery and it starts, the assumption being that it is fit for the road. From your chassis number, you have a very early car so it deserves to be properly recommissioned and preserved. Kind regards, Chris | ||
| John Mann New User Username: ohjohnny Post Number: 6 Registered: 5-2010 |
Chris, That sounds like very good advice. I bought a new set of hoses before the hiatus but I didn't get around to changing them. I guess the brake pressure lamps are not failure proof and the fluid is several years old. I'm not sure I understand 'they may stick on' what 'sticks', the brake itself or the lamp? The brakes did function and I drove a few meters back and forth into the garage. I'll take your point seriously though and perform the recommissioning before any mad dashes down the boulevard. Thanks | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 673 Registered: 6-2006 |
Hi John, I believe Chris means the Brakes stick on (although the warning light switches can stick both on and off) The old flexi hoses close up inside and operate like a one way valve. An emergency / hard stop forces fluid into the calliper but it can not return. The brakes then 'stick on'. You will probably find many threads and articles about it on here. Good luck with her! | ||
| John Mann New User Username: ohjohnny Post Number: 7 Registered: 5-2010 |
Thanks Paul, where would I be without the forum? Johnny |
