i have been digging around the wiring in my 88 dl wagon and according to the fsm there is a diode that goes between the fuse and the ign relay, i tested everything else and all the power circuts work except where the diode is so i unplugged the diode and bypassed it and now have power to the wire. what does that diode do? is it a circut protection or what and what size or capacity is it so i can make a new one. and by the way i fixed the wiring to the climate control fan and it still doesn't work,both fuses are new i was wondering is there a relay and where is it at? i downloaded a fsm and it had everything but the body wiring,found a new resistor pack for the a/c fan at autozone for 47 bucks,iwould like to bypass the resisteres just to see if everything works but it acts like no power not sure which terminal to check,by the way the fusable link is good.

A little more info about where the diode is would help.

 

I forgot to bring my manual to work to scan the heater wiring today.

I think the diode is there to prevent reverse voltage spikes from reaching the ECU and other components.

In the diagram I looked at,it is not between the fuse and the relay though.

 

A 50 volt 1 amp diode should be more than enough.

thanks i think it died and took the ecm out with it,no light on the ecm ever.

I had a bad ground wire under the dash by the steering column not sure which one but I wiggled the bundle of wires an everything lite up now if I can only figure which wire it then gets a battery. my old battery froze because my trickle charger died.

haven't got to it yet as life caught up with me. i will be working on it soon. got new brake pads, hoses new front bearings and seals now for new rotors and calipers. the old ones got red hot. remember on a 87 don't tow the car without the front drivelines.