CEL comes and goes

[Jwbowman0724]

I have an 89 XLT 2.9 5 speed, when I drive it the cel will come on and stay for about 10 minutes then goes out. Does it every time I drive the truck sometimes multiple times in the same trip, I don't have an obd hookup under the dash so I can't scan for codes, I'm just at a loss, anyone have any ideas?

 

[RonD]

Welcome to TRS


You can get the code(s) by installing a jumper wire on the OBD1 connector in the engine bay and then counting the flashes of the CEL in the cab when you turn on the key

You will need to find the OBD Connector in engine bay, in 1989 its probably on passenger side between fuse box and firewall on the wiring harness

Video here: for what to look for: youtube.com/watch?v=RVbDHOiuKpQ

1989 Ranger will use 2 digit codes NOT 3

2 digit Code list is here: https://therangerstation.com/tech_library/2digitcodes.shtml

There are no 0's just 1 to 9


Written version here of the video on how to connect jumper and also how to read codes with test light or volt meter: https://therangerstation.com/tech_library/OBD_I.shtml


If you turn the key off while codes are repeating it will clear them, if you pull out the jumper wire while codes are flashing it won't clear them, your choice

Each code can have different meanings depending on the engine and computer being used
OBD(on board diagnostics) in this case, was developed to be used by Ford techs not DIY mechanics
And the same applies to this day, code definitions are not in "english", lol, they are close but meaning is not always what you may think

i.e. Lean code does NOT MEAN engine is running Lean, it means computers calculations are off, low, so possible vacuum leak

 

[rusty ol ranger]

Or go the easy route and buy this...

20 bucks online. 30 in the stores. Ive used mine extensivly on my 87.

 

[Dav]

does this obd reader need any wire/pigtail to connect it to the truck?

 

[RonD]

No, that reader is for OBD1, 1994 and earlier Rangers, which have a wire connector in the engine bay that plugs into that reader

Connector looks like this: http://assets.mustangandfords.com/f/143084726.jpg?width=620&

But without RED jumper wire installed
It can be on drivers side or passenger side , and may have a cover over it that says "EEC"

 

[Dav]

well, i bought one of those OBD things, just like the one pictured a couple of replies back. followed the directions (there's a first for everything) and am no further ahead.
first time thru it would not believe that i have a 2.9 and said '4 cyl'. i didn't notice that as i was testing so i kept going. got a 41, 74 and 77 code. something with the new O2 sensor, brake switch problem, and operator error-didn't get from passenger side fender to gas pedal fast enough. that's when i saw the 4 cyl light.
took out the batteries to zero the reader and started over. got the 6 cly sign, all code 10 and 11's and nothing else.
i did check the timing with the reader set up; 31 or 32 degrees, which is where it should be. after that it just shut itself off and saved nothing.
tomorrow i will start over.
this truck could drive me to drink, if only it would run well enough to get to the bar!

 

[Dav]

have not had a chance to work on the truck in the last week. but may need it to get to work a couple of days.
can i hook the obd to the plug and leave it there while i drive to work? the cel will come on 5 minutes into the trip but when i turn the motor off, the cel will go out and stay out; when i restart, even if instantly after shutting down, the cel will not come on until i have driven for 5 minutes or so.

 

[Dirtman]

 

[RonD]

have not had a chance to work on the truck in the last week. but may need it to get to work a couple of days.
can i hook the obd to the plug and leave it there while i drive to work? the cel will come on 5 minutes into the trip but when i turn the motor off, the cel will go out and stay out; when i restart, even if instantly after shutting down, the cel will not come on until i have driven for 5 minutes or so.

That will most likely be the ECT(engine coolant temp) sensor, when you boot up the computer it checks engine temp(using ECT) and then monitors it with a timer if its not showing higher temp after 5min it will turn on CEL and set a code

Maybe the IAT(intake air temp) sensor, does the same thing but for air in the intake which should be warmer as engine warms up