Tach stops when flashers are turned on !!

[busybrit]

I'm hoping someone can help me with my electrical gremlin.

Not a Jaguar, but you may have had a similar problem,, I'm working on a 1964 Aston Martin DB5 and both the fuel gauge and the rev counter work fine, but
the flashers and handbrake warning light do not.


When I move the flasher arm to the on position, "up or down," or pull up on the handbrake, the rev counter drops to zero and the fuel gauge to falls to empty.


When I take off the handbrake or put the flasher arm in the middle "off" position both the rev counter and fuel gauge do not come back on.


However, if I turn off the ignition, then restart the car, both the fuel gauge and the rev counter now work,,, until I move the flasher arm or handbrake!


Any ideas????

 

[Geo Hahn]

Mostly clueless but I will ask -- is the tach electronic (i.e. using ignition coil impulses) or simple electric (powered by a small tach generator, possibly on a camshaft)?

 

[LarryK]

Check grounds of each. Check the Red-Purple wires, if any on these circuits. Look closely at ignition switch as it does kill the cycle when used. If any electrical work has been done, recheck. Handbrake and turn signal flasher may have a connection as handbrake light may ground thru the brake switch. If you have a wiring diagrahm follow flow closely.

 

[busybrit]

Problem solved, thought I'd let you guys know what it was. The flashers, handbrake warning light, fuel gauge and tach, all on the same circuit.

When the flashers or the handbrake warning light was activated the bulb/s called for more amps than the circuit was able to supply due to having a loose connection. The power draw resulted in sharing the reduced amps that was available, thus shutting down the whole circuit.

Thx Johnb