Hi, a puzzling fault on my rover. would be obliged if anybody has any ideas. Rover 620 Diesel, V reg. Experiencing dramatic loss of power when lights are switched on. Normal power when off. Totally undriveable if lights on. Won't rev. Tickover always fine. rgds Ian
At a very quick guess, maybe a poor earth on the lights, causing a voltage higher than 0v somewhere on the engine control circuitry?
Check battery terminal voltage with engine running and lights off then on - if it dips below about 13.8V then you might need a new alternator. Other than that, check for damage to the wiring - especially under the dash around the top of the pedals.
Final thought; remove or disconnect the brake light bulbs and try again - the ECU senses the brakes being applied via the pedal switch and if there's a bad earth on the rear lights this might be allowing voltage to that input of the ECU when your tail-lights are on!
Darren
curioser & curioser. Thanks for the pointer,,,,,, seem to be getting somewhere. Both rear bulbs out (dual filament brake/tail lamp), engine runs fine. Earth connection to stud behind trim near offside lamp cluster is fine, but the black cable disappears into wiring loom,,, need to trace in more detail. Did discover though that with either or both rear bulbs in, operating the brake pedal brings on the front sidelights in addition to rear brake lights. Both rear bulbs out, no problem with front lights. It seems to be "earthy" problem, but rear brake & tail lamps seem normal brightness, no apparent dimming of tail lamp when brake lamp or indicators come on ......
continuing to try to trace earths wiring routes.... thanks for pointer.. Ian
On 15/01/2005 15:38:54, in alt.autos.rover, Ian Gaskell licked his pencil and scribbled in message
Did discover
Now that sounds familiar. Change the rear stop/tail bulbs for new ones and see if this helps. I had a 600 that lit the sidelights when the brake pedal was pressed. Turned out to be the filaments in the bulbs touching. They stretch over time apparently.
SOLVED...... Problem was actually a defective bulb. The two filaments had somehow commoned up within the bulb. £1 to fix !! Light switch on & both taillamps & brake lights were on, apparently sending signal to ecu saying "Hey we're braking", thus not allowing it to produce any significant power. Thanks Darren for the original pointer. Not a defective earth, but similar effect. Ian
How odd - I'll remember that for the future !
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