Code Reading Q's

[Clod_King]

So I went outside today to check the codes on the truck. It's been the first nice day in (what feels like) a long time. It's not snowing, the sun is finally out, and I don't have a hang over

So I plugged the reader into the ALDL port, and turned the key to the "ON" position. I got no readings. Not even the manditory code 12.

But I DID get a wierd buzzing sound.... And when I flicked the switch on the reader from the "ECM A-B" setting to the "ABS A-H" setting the buzzing went away.

And when I turned off the truck and unplugged the reader, and then set the key to on position again, the buzzing was gone aswell....

Now I tracked the buzzing sound down to the engine bay. And when my ear was over the air cleaner the sound was loudest. I did NOT remove the air cleaner yet.

The sound COULD be coming from somewhere near the dizzy, because that's where it sounded like it was coming from....


Any help would be greatly appreciated.

 

[readymix]

Could be the IAC making the noise.

 

[Clod_King]

is the noise a sign of bad things to come?

Or is that the noise of it thinking??

 

[dyeager535]

I think your code 12 problem needs fixed first. That's indicating (but doesn't prove) that there is a problem with the ECM.

 

[Clod_King]

So since I am NOT getting a code 12, that means there may be something wrong with the ECM??

How can I check that everything works fine??


I have another thread on here that asks why my truck is not starting right away.

In short:

My fuel pump will not kick in until my oil pressure is around 30 psi, (or just under the 200Kpa mark). BUt after that the engine fires right to life.

Plus when the engine is hot, and I try to get it started it will not always get up to the 200Kpa mark, and then will not start. SO then I have to wait around until it cools down so I can start it.



Every so often while I am driving the "check engine" light come on. Usually on the highway. But that is because I don't travel far with my truck, and when I do, I take the highways.

So I bought a code reader to check that out. And now no codes are being read.

SO if my check engine light comes on, do think I could just pull over, shut it down, and then check it with the reader at that point? because the light does come on sometimes...

Could that mean a loose wire somewhere? Maybe it's being shook in and out connection while I drive....


$h!t I hate electrical work....

 

[blazin_blazer]

when check engine light comes on ecm should store the code why it came on...also the light shouldn't go out w/o resetting ecm???

 

[Clod_King]

THAT'S WHAT I THOUGHT!!!!

So something is obviously screwy... because it'll come on for X amount of time, and then just shut off. SO the next time it comes on, I'm gonna hook up the code reader to see what's going on.

Do you guys thing maybe the wire leading to the check engine light is loose??

 

[Thunder]

If you have to crank your engine till the oil pressure comes up to get it started. Your fuel pump relay is bad. Replace it. It is a black oval shaped box on your firewall passenger side.
For your code reading problem.
Does the CEL come on when you turn the ign to on(but not start) without the engine running?
If so.
Your code reader may be screwed up.
Might want to check codes manually. Its free and you dont have to use one of those POS code readers.
heres how:http://www.troublecodes.net/GM/

 

[Clod_King]

I have already replaced the fuel pump relay with a brand new unit, about a week ago, and the problem has not imporved at all....


And the CEL does not come on at all when the key is in any position....

 

[Clod_King]

I am still gonna try and jump the A & B ports on my ALDL and se what goes down...

 

[Thunder]

If the CEL works but does not come on when the ignition switch in in the on position with engine off. It usually means you have ECM trouble.

Check your grounds before messing with the ECM. Do you have a ground strap that runs from the engine block to the firewall?

 

[Clod_King]

I will check that out.

Thanks man.

 

[dyeager535]

I've taken pictures of the GM R/V manual flow chart pages that deal with no CEL problems, I'll try and get those up tonight. They may or may not help.

 

[Clod_King]

Thanks man, that'd help a tonne.

I have too many problems going on right now... My weekend is gonna be spent out in the cold (a mix of the two..)

 

[dyeager535]

Tried last night, for some reason couldn't get to webshots to upload them. Will try again tonight.

 

[Clod_King]

it'd be real handy if you got that man. Again thankyou.

 

[dyeager535]

Should be the last 4 pics in this album. I suspect A-2 isn't much help, as the GM bold description doesn't make much sense...no ALDL data/no code 12, light on steady? Which is it lol

http://rides.webshots.com/album/561036416UNTMMP

 

[Clod_King]

Okay so I want to clarify something. The CEL does NOT come on at all during start up. I don't know if I specified that, or if i miss led anybody... sorry if i did.

Today on my way home from the CEL came on again. First time in a while (actually the first time since my last post) and it stayed on the whole time right up to where I turned off the truck. The light was on when I tunred off the truck.

Since the light was on I took the opportunity to plug in the code reader. But when I turned the truck back back to the on position, the CEL never came on. No code 12, or anything. It didn't come on at all. And I still heard the clickity-clack sound from the engine bay.

So I unplugged the reader, and started the engine back up to see if the CEL would come on again. But the CEL never came on...


dyeager535, I checked out the wiring diagrams, and I didn't quite understand them. But I will check them out this weekend. I am gonna borrow my buddy's DC volt/amp meter and go probing my truck. But what sections should I check out??

So I geuss what I am trying to say is, the CEL comes on whenever it wants, and the engine performance does not change at all. Nothing weird. And the CEL doesn't seem to retunr after the truck is turned off...




I am supposed to be moving to Saskatoon at the end of april and I would really REALLY like this problem rectified. I don't want to be in Manitoba, and have my truck break down because of something I could've spotted at home...

 

[Thunder]

Try reseting the ECM. Unhook the neg ground cable from the batt for a few minutes. Then hook it up. Check codes to see if you are getting a 12.
If you get a 12. drive it for a while and check codes again.
If No CEL or 12 usually mean a ECM problem.
Might also want to. Check that all the wires to ALDL port are hooked up. Mabe the wires to the a and b ports have becone disconnected.

 

[Clod_King]

I will check out the A&B wires.

the ECM has recently been reset. last saturday i disconnected it and pulled it from the truck to remove the inner fender so I could remove my heater/ a/c system. So that isn't the problem.