We have a 1990 B150 (conversion van) with the 4 pin ASD Relay. the wire colours are DK blue, Red, Dk green And Dk blue & yellow. The engine would not start so we bought a couple of ASD relays incase of bad parts, but no luck yet. however when we bridge the Dk blue and red wires on the relay the van starts and runs normal.

According to the haynes Manual the wiring is

Dk Blue - Smec (single module engine control)
Dk Green - Fuel tank Sender unit
Red - Charging Circuit
Dk blue/Yellow - Diagnostic Connector (however the wire is missing at diagnostic plug)

DK blue & Red wires unbridged with the ignition on there is no service light and no start.
DK blue & Red wires Bridged and it works & starts but we can't pull any codes..

We assume this is the ASD as it is the only relay between the battery and the Brake Servo. If not where is it. We have also replace the part throttle unlock relay as well to no avail.... been at it for months and getting nowhere.... Thanks in anticipation....

 

The wires of interest should be the Dark Green and Red ones. The red is the main power from the battery. You should have battery voltage from the red to ground, with the key on or off. The dark green wire is from the relay output, meaning that this wire should be powered only when the relay is energized. These are the 2 wires you should be jumping out for testing purposes.

The dark blue and dark blue/yellow wires go to the coil of the relay. There should be 12 volts across these two wires only when the key is turned on.

 

Thanks again for that will check it out.....

 

Checked it out and found the problem.. It was the fusible link in the read wire. runs sweet now also for future reference any ideas where the fuel pump relay is, if not no matter....thanks again..

 

Your's doesn't have a separate fuel pump relay. The ASD relay turns the fuel pump power on and off.

 

I guess you should've asked months ago.

 

yeah quess so... Just put it down to experience.... Thanks again mate....