I know this might be a long shot for diagnosing but any ideas are helpful. So i'm driving yesterday doing about 35 and my check engine light comes on. Maybe an O2 sensor going bad? Catalytic converter getting plugged? Every time I start it up, the light isn't on until i start driving and the rpm's reach about 1200, then it comes on. It still runs fine which has me questioning my O2 and catalytic converter ideas. I'm also no mechanic as far as diagnosing things goes so any knowledge is welcome! thanks guys

 

Need the code(s). http://dodgeram.info/Engine-Gas/OBDI/pcm_fault_code.htm

 

go to an auto store they all run codes for free and tell you what sensor it is then show you on computer where it is located at makes doing it yourself not so hard.

 

And get a Haynes manual while your there.

 

For sure i had a 97 F-150.. Chilton's was my best friend even tho i pretty much only used wiring diagrams still is a good investment

 

ok Ive done the ignition on/off trick and it has not helped me. this is how it read, the ones will represent flashes and underscores represent pauses...

111_11111_11111_11111_11111

from what i understood on the link provided a few responses ago, the last numbers will be 55 which means end of the code and there can only be two numbers for the code itself. I have three in this case? Could I have read it wrong (I read it twice and got same result)? Before the 55 there were 13 flashes all together. And doing the math on that link there are no codes where the two numbers add up to 13...? Im confused.

 

I guess that would be a 13 ? MAP sensor vacuum problem, check the hose going to it. Also , if you remove it you will see a very small right angle hose, make sure that is not dry rotted or anything.

 

I'm thinking you put another 5 in there on accident

From what you stated, the code would be 355. If memory serves, on the older trucks (like yours) you add the numbers in each group separately to determine the code number. so you got 3 in the first spot, 5 in the second, and 5 in the third (I think you accidentally put this extra 5). Then it does 55 to signal the end of codes.

So, if my assumption that you were superfluous with the 5's is correct...

You got yourself a code # 35-- idle switch motor fault. I think this is referring to the iac, or the connections therein. Check the pigtail that leads to it (on the backside of throttle body). If your problem isn't solved by this, try cleaning the IAC along with the rest of the throttle body. Whatever you do, dont push the shaft in to the solenoid, then you'll wind up needing a new one.

Quote from the linked site stating how to check codes: "As an example, a stored code of 23 would flash 2 times, pause, flash 3 times, pause, flash 5 times, pause, and flash 5 times." You dont add the flashes together, each group of flashes represents a separate number. The last two 5's signal the end of stored codes.

So glad Mine's an 01, much easier with the digital readout

Hope that clears it up.

 

These are the codes for a dodge ram. 35 is not for IAC, 25 is. So I don't know what's up with the way the OP is counting the flashes.


http://dodgeram.info/Engine-Gas/OBDI/pcm_fault_code.htm

 

Didn't know obdI was different between vehicles. Got that 35 from a jeep site (didnt know the link already posted had them.... maybe i should start scrolling down more often)

According to this, its "radiator fan low speed relay circuit".... Which makes no sense at all.

OP, can you get a video of your truck flashing the code out?

Or maybe take it to a parts store and get them to scan it (usually free at orielly's, autozone, etc.)