Dodge Repair: CHECK ENGINE/ OBD Location?: 88 D100, dodge d100, engine controller

Question
I have a 88 dodge d100 that my friend passed on to me, it's not much to look at on the outside but the truck runs really well....the only thing is the "check engine light" goes on as soon as I start to drive it.

My question is how do I know what the light is for and does it have an OBD port (location)/


thanks

Answer
Hi Jhun,
In the late 80's the OBD-I system was in effect. There is a 6-pin rectangular socket (4 in a square plus 2 on the edge of the square) into which a code reader can be plugged to find out what the engine controller has stored in its memory regarding a fault. It is a different-shaped socket from today's OBD-II 16=pin socket which is located under the dash. The OBD-I socket it located in the engine compartment, usually on the left side near the firewall and engine controller and a code reader with a plug and programming for OBD-I readouts is plugged into that.  
You can do a self-readout of the memory for codes without a code reader by using the ignition switch; turn the ignition key "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then observe the check engine light, which remains "on", to see it begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat procedure to be sure of an accurate repeatable set of flash counts. Tell the counts in order of appearance and we'll go from there.   Also tell me which engine (L) you have.
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Thanks,
Roland