Can't seem to correct this issue. In the process of replacing all ground straps on motor/frame and freshening grounding screws in dash/radiator support. Re-splicing connections. Can't find a rubbed wire. Any insight is appreciated.
'67 bird (convertible) rebuilt by past owner, 3,000 miles ago. Electric fan located in front of Be-Cool radiator. Toggle switch on dash for fan. Fan works perfect. Summit Racing 3 gauge cluster ... voltage, temperature, oil pressure. Works great.
With engine running, either driving or at idle at a light, gauge cluster works fine, all #s appropriate, temperature reads 190-210. The moment I turn on the fan, gauge needles jump, temp immediately reads 220-230, and voltage changes too. This is an immediate and sudden jump in the gauges with the toggle switch on/off. Then, the needles slowly come down over minutes .... but not back to baseline, with fan on. Oil pressure gauge seems least affected. Turn the toggle off, temp drops on gauge 15-20 degrees instantly.
Thoughts on troubleshooting ? Gauge cluster grounded to metal dash, electric fan grounded to radiator brace. Grew up in my dad's 4 bay 24 hr Shell service station, but electric gremlins are my weakness for sure. My experience tells me bad ground ... but I can't find it for the life of me. Any grey haired wisdom would be appreciated ! Thank you
