Klima relay if equipped (without R4 compressor). It handles both the tach signal and compressor RPM sensor for comparison for belt slip. Pull it, pop the top and see if it desoldered, eith that or try one.
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.