elctrical issues need help asap

[bowanna03]

I have a 1998 gmc jimmy with the 4.3 having some issues when i start the truck i am only getting oil pressure and battery gauges are work ing nothing else is working the truck starts and runs fine but when i am having this problem the truck is slow moving almost like it nots shifting maybe because the speedo isn't working but if you push in the trip reset button and hold it all the gauges stay up but as soon as you let the button go they go dead i checked all harness's grounds, battery, and even put a new ecm in it and it still does it any help because if i dont get any help. i get rid of it also the key will not release out of the ignition also

[GM-Tech]

Sounds like a possible ignition switch (not the lock).

[bowanna03]

would this cause the dash to act like that someone on another forum told me to check the ignition module could it be that

[bowanna03]

the mechanic said its also throwin tranny codes what can cause that maybe the fact that the speedo isn't working

[GM-Tech]

An ignition module would not affect the dash. The trans is controlled electrically so loss of ignition power to the trans would cause the trans to default to 2nd gear starts. This makes it VERY sluggish. It also causes about 4 trans codes to set... one for each solenoid due to power loss.

 

EXACTLY what all doesn't work when this problem occurs? It also sounds like it could be a class 2 data problem, though I don't quite understand why pushing the trip reset causes the gauges to come back.

[bowanna03]

what do you mean about a class 2 data problem

[GM-Tech]

what do you mean about a class 2 data problem

 

<{POST_SNAPBACK}>

 

 

 

All the modules in the vehicle (PCM, BCM, Cluster, etc.) are connected together into a network via a single wire and data is sent over this line by a protocol known as class 2. They all talk to each other, sending various bits of information.

 

For instance, the cluster gets much of the information it needs from the PCM via the data line. For instance, among other things, the PCM sends speed info, engine temperature, PRNDL position, to the cluster.

 

If the data line is grounded, shorted to power, etc., the data line will be down and the cluster (and all other class 2 devices) will not get the information it needs. The various gauges (not all are controlled via the data line) that need this info would just sit at zero without that data.

 

This is pretty easily determined with a scanner that can look at EVERY module. If you can read the data in the PCM, for example, it's not a global data line problem because the scanner gets its information to display over the same data line. It could, however, be a data problem within a particular module that does not affect the data line in general.

 

It would be relatively easy to determine if there's a data problem with a good scanner. All modules are monitored and if one cannot be communicated with, all the other modules would have a "U" code in them indicating they lost communications with the dead module.

[bowanna03]

my mechanic replaced the ignition module to day and sia its still doing it so that didn't fix it anything else that comes off the top of your head at all that it could be

[GM-Tech]

my mechanic replaced the ignition module to day and sia its still doing it so that didn't fix it anything else that comes off the top of your head at all that it could be

 

<{POST_SNAPBACK}>

 

 

\

 

 

Do you read what's been written in response to your questions? I'm wasting my time answering if you're going to ignore it.

[bowanna03]

im sorry im just getting frustrated the problem is when i start the truck i only get the oil pressure gauge works the voltage gauge works and all the others dont work but if you push in on the trip odometer reset button and hold it all the gauges coem up and work as soon as u let go they shut off but the truck stays running and when u try and put in drive the truck becomes sluggish and barely moves kind of like what u said likes it starting from 2nd gear also when u shut it off you cant get the key out of the ignition you have too wait a while or turn it on turnit off back and forth a couple of times then it will come out. also i notice if you push in on the brake and press the button on the shifter the lights also work and then let go and they go off

[GM-Tech]

You're saying almost exactly what you said in your first post. Nothing new there. I already gave you one opinion of what I thought it MIGHT be.

 

 

im sorry  im just getting frustrated the problem is when i start the truck i only get the oil pressure gauge works the voltage gauge works and all the others dont work but if you push in on the trip odometer reset button and hold it all the gauges coem up and work as soon as u let go they shut off but the truck stays running and when u try and put in drive the truck becomes sluggish and barely moves kind of like what u said likes it starting from 2nd gear also when u shut it off you cant get the key out of the ignition you have too wait a while or turn it on turnit off back and forth a couple of times then it will come out. also i notice if you push in on the brake and press the button on the shifter the lights also work and then let go and they go off

 

<{POST_SNAPBACK}>

 

 

[bowanna03]

it was the ignition switch