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When LOGGED-IN. Go to upper right hand corner of screen. Click on Username. Click on Account Settings. Find and click on Signature. Add vehicle information here (YR, ENG, TRANS, etc, etc) then click on SAVE. This helps everyone. This information will be available every time you post.

Good find. Nicely done.

No it is not a output circuit. ECU C201_C2 is a input circuit. It will either see voltage or see no voltage. Its a voltage sense circuit. Same thing applies to ECU C201_D2.

I'm using the 88 Electrical Manual, which has been known to be wrong. So In order to keep us on the same page check out page 37. _mj1988electricalmanual_1.pdf If you show Pin 86 having B+, then maybe Pin 85 is the grounding leg for the AC relay.

Is AC relay installed? if so, remove it and retake B+ readings on Pins 85 & 87. Engine RUNNING and AC selected.

Pin 85 is a Fuel Pump Relay feed (B+). With KEY ON you may only have B+ for 2-3 seconds only. Try taking reading with the engine RUNNING.

Remove and clean the IAC motor. Clean throttle body cavity that the IAC lives in. Could also be just slow response time on your existing IAC motor.

Those will NOT cause engine vacuum leaks.

B+ Latch relay uses that FL link to supply B+ (battery) voltage for IAC motor drivers (on ECU). Also resets IAC during KEY OFF for next START.

Okay, that proves the ECU C202_B10 supplied the 12vdc (B+) for D2_5 and B+ Latch relay was picked (activated) by the ECU C202_A9. Using a fused jumper wire connect the FL eyelet to B+ (battery). START engine, does Idle Air Control (IAC) motor help with engine IDLE?

Of all the relays used on these vehicle, B+ Latch relay is the strange one. When you tested for voltage on D2_5 with engine running was the fuse link hooked up to the starter relay?

I was only talking battery. True. block head to firewall. I don't believe factory came with B- negative to fender. Could be wrong here.

Only ground should be B- negative to engine block.

Yes

Yes. At the Starter Relay Bolt. Wait. Do D2_5 test first.

With engine RUNNING, does D2_5 show B+ (battery) voltage?

Could be FL for B+ Latch Relay. On start up does vehicle idle soar and come down after CRANK?

Renix Engine Monitor (REM)

Do you have a RENIX Engine Monitor (REM) or some other way to look at ECU serial data? Make sure you're getting the most with what you already have (baseline).

Kinda of TRUE. Its in play only in the sense that it supplies ≈9-10vdc (voltage drop across ballast resistor) during engine RUN and CRANK (Fuel Pump Relay is ON). Now during engine CRANK the Starter Relay terminal (BAL) is wired to bypass the ballast resistor and supply direct battery voltage to fuel pump. During engine CRANK higher voltage wins.

Mystery solved. I'll sleep better tonight. Thanks to all.

Ohhhhh, now I'm starting to catch on. It's a finger/thumb protector.

So somehow its meant to hold, say a box of wood stick matches or maybe a pack of pocket matches? I find this interesting in a good way.

I've noticed on many gas BBQ units this part or something similar to this hanging from a chain. I believe it has nothing to do with the drip pan and its to flimsy to hold anything heavy. What is the purpose of this part and how does it work?

Gauge Cluster lights are controlled by the dimmer switch on the headlight switch. Switch maybe set to OFF. Rotate the knob from one end to the other end.