"I got a code of 1-3-1 (engine rpm signal missing) when the wires to my original RPM sensor went bad."

That confuses me Dan, but it might be sloppy terminology in Bentley. Did you pull that code 1-3-1 in Mode 1, or did you get it while exercising components in Mode 2? If Mode 2, maybe Jarrod misread 1-3-1 as 2-3-1???

I base this on the Regina FI green books ( Wiring Diagrams and Fault Tracing.)
The WD book also has the LH ECU diagrams for both B230F and FT. Neither of them show any direct connection from the "RPM" sender to the LH ECU. Only to the EZC ignition module.

The EZK CU does however send an "engine speed signal" (Rex/Regina term) to the LH ECU, just like the REX ignition "signals" the Regina ECU. The same way that all Bosch FI systems require a continuous "OK" from the ignition for start and run.

If your bad RPM sender failed to "report to" the EZK (#1), then EZK couldn't relay the "speed signal" to the LH ECU (#2). Looks to me like #1 means an automatic #2.

But #2 could occur without #1 (separate EZK—>LHsignal). I think we has a long thread on such a failure a few months ago ("Who let the dogs out"?)

Bruce


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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.