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At idle, timing is base timing. As you throttle down, timing is advanced and if Distributor Indexing is incorrect, crossfiring occurs. The trailing edge of the rotor must be at or just pulling away from the #1 tower. I notice cut lockdown tangs.

Double check Distributor Indexing.

Yeah, from manifold to MAP sensor.

Your symptom sounds like you still have a Distributor Indexing issue. Check MAP hose again.

Looks like C109. Engine Harness to Engine Control Harness. Next to RH shock tower.

Pull the HAZ/STOP fuse out. Determine if one terminal or the other terminal has 12vdc (testlight will also work) on it.

At 3:28 IP cluster view: What's that gauge in the lower right? Something for the diesel, turbo boost maybe. If so, was that electronically controlled?

I wonder if the Fuse Block was back-filled with all necessary fuses, regardless of what options were chosen by the customer.

Check your fusible links located on the starter relay. Check for open, bubbles or burnt links.

My mistake, you can't eliminate the dimmer control circuit. Always there when in PARK, LO BEAM or HI BEAM. Will not matter what position (rotated L or R) it's in.

Back to normal. Looks good.

You might want too keep your dimmer switch in the OFF position when using your PARK or LO BEAM's until you find the HI BEAM problem. Since you installed the Headlight Relay fix, it won't draw high current thru the Headlight Switch anymore, but it will trip the HI BEAM relay, unless dimmer is turn OFF.

Things always come out easier the second time around.

It ain't doing you no good the way it is. Gently, Gently. Try it on just one first.

That last photo could be area of concern. Also seem like bulb sockets, when locked in, have worn thru the foil. Check bulb sockets for good contact at terminals.

You are reading voltage that drops across the dimmer variable resistor (rheostat). 10.68vdc should be enough to light the lamps. With good voltage and good ground, problem may lie on the printed circuit foil on the back of the cluster. Look for any open circuits there.

What I was wondering is, when your LO BEAM's were ON did the Instrument Panel Lamps circuit power the HI BEAM circuit (melted C269_1) at the same time. Yes, your going to need/be a Harness Surgeon for this one. Instrument Panel Harness is difficult to deal with. Nothing easy here.

Should be good here. Check for voltage (12+) on the following pins: C203_1, C203_4, C203_9 and C203_16. Make sure Headlight Switch is ON and dimmer control is set to the brightest. Page 61 in the manual.

Do a search for "insert boot disk". Lots of information. May help.

Seems like that burned out HB indicator bulb hid the fact that your HI BEAM's were also ON with your LO BEAM's. Did oncoming traffic at night ever flash their lights at you? 88 Electrical Manual call the Instrument Panel Lamps circuit (WHT) and the HI BEAM circuit (ORG/BLK). Short is wherever those two wire run together within the Instrument Panel Harness.

Do you recall if the HI BEAM indicator was lit (IP Cluster)?

I think what you just posted explains why Headlight Switch C269_1 melted. I believe your shorted between HI BEAM circuit and Instrument Panel Lamps.

Need to make sure you can't dim your HI BEAM's with the dimmer switch. Also check and see if the dimmer dims the Instrument Panel Lamps.

Instrument Panel Lamps are more than likely finding the proper grounds. My question now is the voltage sources. 1) Panel Lamps that work with HI BEAM, yet shows no dimmer control, means HI BEAM circuit is shorted to Panel Lamps between Headlight Switch and Panel Lamps. 2) Headlight Switch C269_I (melted terminal) could be the cause for no Panel Lamps, but what caused the high current to melt it. Don't think that the terminal (C269_I) is the one that melts with high current flow thru Headlight Switch. Seems compound problems here, HI BEAM short to Panel Lamps, No voltage thru Headlight Switch (dimmer circuit) for Panel Lamps. Need to trace the HI BEAM circuit for short to Panel Lamps. Should solve this one first.

This question is more out of curiosity. When HI BEAM's are ON, using the dimmer switch, can you dim all the Instrument Panel Lamps?