Need help asap.

inline6power

more hp than you
Joined
Apr 15, 2007
Messages
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Well on my 99 p pumped trick has a problem. For the last few days when I go to start the truck the only gauges that work are the speedo and fuel Guage. Everything else is at zero. Oil tach temp and alt. After about 5 minutes of driving everything will kick back on. When I try to check with scanner it won't connect to truck. Sometimes it will while most other times it won't. Is this a sign of the ecm going out or will a sensor like the crank sensor cause this.

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Well on my 99 p pumped trick has a problem. For the last few days when I go to start the truck the only gauges that work are the speedo and fuel Guage. Everything else is at zero. Oil tach temp and alt. After about 5 minutes of driving everything will kick back on. When I try to check with scanner it won't connect to truck. Sometimes it will while most other times it won't. Is this a sign of the ecm going out or will a sensor like the crank sensor cause this.

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It could be a loss of bus communications, a short or open, a failing module (ecm/pcm) is also a possibility as is a cluster. I would start with powers and grounds, iod fuse, the basics before digging in the big stuff.

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Also when the gauges are not working my ac also does not work

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My 2000 would do that, I would just push on the cluster and everything would kick back on.


My AC would work though... not sure about that one...
 
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Also when the gauges are not working my ac also does not work

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With that said I would consider checking voltage and grounds at the pcm while the problem is occurring. Determine if the a/c clutch is engaging . That will point you somewhere.

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Chits killing me lol. Every time I start it now the gauges don't work. Then after driving for say 5-10 minutes it will all kick back on then stay on rill I shut the truck down again. Not sure where to look

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Chits killing me lol. Every time I start it now the gauges don't work. Then after driving for say 5-10 minutes it will all kick back on then stay on rill I shut the truck down again. Not sure where to look

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Its always a good idea to check all fuses and make sure they are making good contact and not blown. You'll just have to work through it till you get communication. Typically when everything started working the communication would likely return if the issues are related.

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pull your cluster check connections then reinstall..
There are a couple plus that do not have keepers. Just retention from screws on cluster..
Maybe pull and install a couple times to get you to fresh contact.
 
How could the Guage cluster keep my ac from working? Also tested with an volt meter, truck does not charge when gauges don't work either. It's almost like the ecm pcm is not getting power since they control the charging and ac stuff. Once they kick on then all is good. Driving me crazy lol. Just not sure how a Guage cluster could cause the other problems. If it were a fuse it would happen intermittent but once the gauges kick back on they all stay on until I shut the truck off again.

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Girlfriends truck did the same thing, everything wouldn't work then sometimes it would. She had installed her radio by herself and left a wire dangling and every so often it would short out, but where her mileage reader is it always said no bus just as mysterync said.
 
My odometer has never said no buss yet. It always has my miliage showing it's just all the other stuff going on. When the gauges don't work it still shows my miliage and it has never said no buss that's what's got me really confused

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With that said I would consider checking voltage and grounds at the pcm while the problem is occurring. Determine if the a/c clutch is engaging . That will point you somewhere.

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Which wires power the ecm and pcm and what wires are the grounds? That will give me something to check while it's doing it

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Which wires power the ecm and pcm and what wires are the grounds? That will give me something to check while it's doing it

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Sounds like the ground for the PCM. It does ground through the hold down screws. I had the same problem with mine a while ago, pulled the PCM and scuffed the mounting points behind the screws and no problem since. A shorting sensor can cause the same issues, but normally it will give the NO BUS as well with a shorted sensor.
 
Sounds like the ground for the PCM. It does ground through the hold down screws. I had the same problem with mine a while ago, pulled the PCM and scuffed the mounting points behind the screws and no problem since. A shorting sensor can cause the same issues, but normally it will give the NO BUS as well with a shorted sensor.

X2.
I'll try to post a diagram when I get a second.
The pcm also grounds through various wired grounds. Without seeing the message no bus I have a feeling your lack of scanner communication is likely a blown CIG lighter fuse.
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How could the Guage cluster keep my ac from working? Also tested with an volt meter, truck does not charge when gauges don't work either. It's almost like the ecm pcm is not getting power since they control the charging and ac stuff. Once they kick on then all is good. Driving me crazy lol. Just not sure how a Guage cluster could cause the other problems. If it were a fuse it would happen intermittent but once the gauges kick back on they all stay on until I shut the truck off again.

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its all ecm related, cluster and ac working..
Worth a shot due to age..
Just trying to think of what i came across pulling apart that stuff to put in the car...
 
so does this sound like a ecm or pcm problem? i am thinking its ecm related but not sure.
 
its all ecm related, cluster and ac working..
Worth a shot due to age..
Just trying to think of what i came across pulling apart that stuff to put in the car...

The a/c will still function without the cluster. The a/c clutch is controlled by the pcm (not ecm) on circuit c13 db/or.
I imagine it could possibly cause an issue but its not controlled via bus. All solid state, you turn the switch, pcm senses voltage on the circuit and turns on the clutch relay and begins to monitor the pressure circuits. Not saying the cluster isn't part of the problem but not likely causing a/c issues unless something shorting to ground. Even then most transistors will default to off and indicate a circuit failure.

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