Oil pressure, tach, coolant temp gauges

87targa

New Member
Nov 14, 2005
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Utah
the oil pressure and coolant temp gauges were working before i did a heater core replacement. I replaced the heater core, put things back together and now the oil pressure and coolant temp gauges do not work. I have checked the gauge itself and the resistances are fairly close to the TSRM -- off by 2-3 ohms for both gauges. i checked the coolant sending unit resistance and it's erratic. i have not checked the oil pressure sending unit yet. But for the oil pressure gauge, i have checked the harness in the dash with a volt meter. i get 0.3 to 0.7 volts during idle.

for the tach, while doing the heater core, i wired up timing control for the maftpro. would that cause the tach in the dash not to work? i don't really think it would since the rpm reading on my turbo timer works but is off by 300 rpms when compared to the reading on the maftpro.

I also wired in a LC1 w/b o2 to the maftpro. I don't think that would cause an issues with the gauges?

does anyone know what would cause the gauges in the dash not to work?

thanks