Ωhm

FYI stuff. Hope it helps. Bosch PFI Noid Light OTC 7188 Found this some time ago and YES injector drivers get HOT, that why they mount them on HEAT SINKS.

KEY OFF. Check for continuity between: ∙D1_3 and D2_7 ∙D1_3 and Battery Negative terminal ∙D2_7 and Battery Negative terminal Looking for continuity. (≈0Ω)

That sound good, acting as designed. So, shooting starter fluid down the throat and cranking engine still give nothing? No kicking. No bucking.

Just what does this mean? I've now learned that B+Latch Relay is more than just for resetting the IDLE motor (4.0L) at ENGINE OFF, it can also cause a ENGING CRANKS, NO START condition. @GrandBoost98 @Glenn Bint

Had one ↑↑↑ show up at The Dearborn Classic Car Show on Saturday. YR?? unknown. Requirement: 1995 or older.

D1_5 is HOT AT ALL TIMES. Key position will not matter. Yes.

My guess would be LOW/HIGH speed fans. Maybe something for a winch.

Don't do that test yet. You must remove the AC Clulch Relay first.

The REM uses the block sensor for coolant temperature. Engine Coolant Temperature (ECT). No. AC needs to be fully functional otherwise ECU will not pick AC Clutch Relay which also feeds Cooling Fan Relay. EDIT: Do not test

Numbers tell me your running RICH. Look for those kinds of causes and that includes the Air Filter.

do you have a wiring diagram handy? are the seatbelt wires a ground? @Pete M 88Electrical Manual. Not sure if this is what you're looking for.

You are correct. I was looking at RENIX 88-90. oops!

Check ETR fuse (10AMP). Common to both Clock & Radio.

Determine which Relay is the B+Latch Relay (Power Latch Relay). Look for your block relays, should be 2, 3 or 4 relays locked together. PIN_4 & PIN_5 should have PINK wires. Pink should help with relay ID. Example is 4.0L engine. ECU connector C200. If you PASS the three (3) pinpoint tests and you know your B+Latch Relay is good, next step would be to try a known good ECU. Since engine STARTS and RUNS with jumper wire in place. Could be/should be/ maybe OKAY to swap ECUs. Do you feel lucky.

HOT AT ALL TIMES doesn't care if KEY ON or KEY OFF. Continuity testing needs KEY OFF. KEY OFF. B+Latch Relay removed. Disconnect C200. This testing will require extra-long leads used for DVOM (ohmmeter). Check for continuity between C200_7 and C215_2. Check for continuity between C200_19 and C215_4. Check for continuity between C200_19 and C215_5. If continuity exist between all three (3) pinpoint tests, suspect ECU.

The Blower Fuse (25Amp) is common to both the Blower Motor and the AC clutch. When problem exist do you lose other things like Wipers, Turn Signals or Radio or maybe all three (3) at once?

Take them two (2) measurements mentioned above. D1_5 and C215_1 (remove relay) should show HOT AT ALL TIMES.

Is that pin_4 on the relay?

Yes. Any electromagnetic sensor (CPS) decrease in gap will increase AC voltage output, but to close can confuse it. Engine cranking or engine running speed (RPMs) has a greater effect on AC output. Increase RPMs increases AC output.

Using a voltmeter or 12vdc testlight (preferred) check for Battery_Voltage (B+) on the following pin (use battery_negative terminal for ground): D1_5: B+ (Hot at all times) Determine which Relay is the B+Latch Relay. Check for HOT AT ALL TIMES on PIN_1 (RED). PIN_4 & PIN_5 should have PINK wires. Pink should help with relay ID.

You guys need one of these? Plastic, license plate size.

Nice job on your end with the pinpoint testing.