What are these plugs for?

[RangerGoolz]

I have three unplugged plugs on the left side of my engine bay. They are between the airbox and firewall. Does anyone know what these could be for? One thing I am realized in the month I have had my 86 is that even when I turn the key on before completely starting I never see the engine light light up. Not at all ever. I have seen in youtube videos of same years and when people start their cars the engine light briefly comes on. Did the previous owner unplug it somehow or? Anyone way I can test it? The truck runs really well. Starts and idles great. Just continuing to learn as much about the truck as I can because I absolutely love it. Thanks all.

 

[rumblecloud]

The grey and red are for system diagnosis using OBD1 code reader. I didn't think that was available on pre-93 or 94. Not sure what the other one is for. But someone will come along shortly and correct me, cuz I'm usually only part right

 

[alwaysFlOoReD]

86 is the first year of EFI. There wasn't any cel light for this year. As rumble cloud said, the grey and red are for obd1 diagnostics. The black is for a relay, I think for air conditioning bypass when gas is floored.

 

[AndyB.]

Two of the connectors plug into a scanner like this.

The bulb may well be burned out. The light was originally switched on by a module that was a timer set to turn on around 60k miles. It can be accessed by dropping the glove compartment and looking up. There’s a paper tagged labeled reset that gets punched through when the module is reset.

 

[RonD]

+1 ^^^

Yes, no CEL(check engine light) on your year

Grey and red are for testing the computer, commonly called OBD1 connectors, they are left unplugged until needed
Seen here: https://www.therangerstation.com/tech_library/OBD_I.shtml

The labelled Fuel Pump slot can be used to activate the Fuel Pump Relay manually for testing purposes, if you GROUND this slot, then when you turn the Key On the fuel pump relay will activate and send 12volts to the TWO fuel pumps
Normally, the computer grounds that wire/slot with key on but ONLY for 2 seconds, its a safety thing, so makes it hard to test wiring to fuel pumps


The black one may be for an uninstalled Option, need to see/get the wire colors on it to see what it might have been for
It looks dirty inside so hasn't been connected, ever, or for a very long time

 

[RangerGoolz]

Thanks so much all. You have cleared up some major concerns. Now I would like to purchase an OBD1 reader. Any links for a decent affordable one?

 

[AndyB.]

There’s no need to buy a dedicated scanner, you can do just as well with an analog multimeter.

 

[RonD]

Or a 12v test light

OBD, on board diagnostics, is a communications "protocol" a Language, like French
French 1 didn't have enough "words" for the newer/larger engine computers coming out
So English 2 was decided on as the new common language for vehicle computers
So not the same language at all so different translators are needed

OBD1 hasn't been used since 1995, all new vehicles sold 1996 and up were required by law to have/use OBD2(OBDII)
So there are going to be a lot of the OBD1 readers around but not used too much anymore

Ask around someone may have one just sitting around, they don't go bad
Look on local craigslist for OBD1
Garage sales with auto parts as well
I have seen them at wrecking yards as well, found in old vehicle's glove box or ??

OBD1 Ford codes seen here: https://www.therangerstation.com/tech_library/2digitcodes.shtml
You will notice there are NO codes with 0, all are 2 digits and only use 1 to 9 so you can "read" them with a test light or volt meter
There are some codes like 40 or 80 but they are for a specific Ford vehicle computer, wouldn't be used on a Ranger computer

OBD2 Codes seen here, all car makers had to use the same P0xxx codes: https://www.therangerstation.com/tech_library/OBD-II_codes.shtml

English 2 has ALOT more codes than French 1, lol

 

[Cees Klumper]

Innova 3145 is a good and easy code reader with a good manual in this case. I see for $30 on Amazon