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98 c5 6mt cruise control wont work, and cant get rid of po443/po803

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98 c5 6mt cruise control wont work, and cant get rid of po443/po803

 
Old 05-17-2019, 11:10 PM
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Empire087
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Default 98 c5 6mt cruise control wont work, and cant get rid of po443/po803

So long story short, bought a c5 that ran, but not much else, and have been slowly but surely fixing all the crap ive found wrong with it(the list is LOOOONNGGGG). I have however finally been able to get it on the road only to find a few problems that are really bugging me.

First and foremost, i cannot figure out why the cruise control does not work. It was recommended that i adjust the cc pedal switches to make sure they are fully pressed in. Well after doing that today my cruise control worked for about 15 minutes and i was thrilled. Well after i drove through town and shut off the car my cc stopped working again. Figured id pull and clean the contacts on the inside with a brass brush and some contact cleaner. reinstalled all 3 switches and still not working. Any idea where to go from here? Been googling my brains out and not getting anywhere.

next ive had a persistent set of codes, a po443 and a po803. The purge solenoid valve ive replaced and the problem still is around so its obviously not that. The skip shift i had when the solenoid was hooked up as factory, well the car came with two skip shift eliminator kits well i tried them both with the code still poping up as soon as the car starts up. The car has the air pumps deleted, aswell as the cats, and thats all tuned out. I did see something that said both of these things where on the same circuit as far as fuses go, is there any truth to this? The fuse i thought it said it was did not appear to be blown, but i also checked that this morning.

Been trying facebook, but it doesnt seem like the knowledge is there compared to using forums. Fingers crossed you guys can give me a solution for these problems!

Thanks,
Dakota!
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Old 05-18-2019, 07:32 AM
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I don’t have much time to comment on this right now but as far as the P0443 (a circuit issue) goes not checking the wiring was your first mistake...you can remove the connector and with key ON see if you have battery feed voltage going to the PINK wire..if you do you most likely have issues with the control circuit which is the other wire...the control wire is “ground side switched” which means the PCM “internally grounds” the control circuit to make the purge valve open and close...a Tech 2 or bi directional scan tool (needed to activate the driver) and a 12 volt test light is all you would need but I doubt you have one...you can back probe (a needle would work) the back of the control wire with the connector reinstalled and again with key ON you should see 12 volts on that control wire if everything is good BUT the driver may not be grounding the circuit (bad PCM) when it is supposed to during its EVAP test OR you have an open in the wire between the PCM and the connector...being that you already replaced the purge valve if you see 0 volts on the control wire (indicating current is flowing through the wire and purge valve) either the computer “driver” is stuck on (possibly bad PCM) or a shorted control wire somewhere between the connector and the PCM !!....I’m thinking if you remove the connector with the key ON and you hear the purge solenoid click you most likely have a shorted control wire or bad computer driver...also if the purge valve is stuck open all the time the car will run poorly after you fill the gas tank because the fumes from the EVAP canister is causing the car to run RICH after being drawn into the intake manifold !!...I bet you don’t have 12 volts at the pink wire !!

Last edited by C5 Diag; 05-18-2019 at 07:03 PM.
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Old 05-18-2019, 08:54 AM
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your cruise control switch is probabl striped , replace it and I bet you will have c/c
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Old 05-18-2019, 04:05 PM
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Originally Posted by C5 Diag View Post
I don’t have much time to comment on this right now but as far as the P0443 (a circuit issue) goes not checking the wiring was your first mistake...you can remove the connector and with key ON see if you have battery feed voltage going to the PINK wire..if you do you most likely have issues with the control circuit which is the other wire...the control wire is “ground side switched” which means the PCM “internally grounds” the control circuit to make the purge valve open and close...a Tech 2 or bi directional scan tool (needed to activate the driver) and a 12 volt test light is all you would need but I doubt you have one...you can back probe (a needle would work) the back of the control wire with the connector reinstalled and again with key ON you should see 12 volts on that control wire if everything is good BUT the driver may not be grounding the circuit (bad PCM) when it is supposed during its EVAP test OR you have an open in the wire between the PCM and the connector...being that you already replaced the purge valve if you see 0 volts on the control wire (indicating current is flowing through the wire and purge valve) either the computer “driver” is stuck on (possibly bad PCM) or a shorted control wire somewhere between the connector and the PCM !!....I’m thinking if you remove the connector with the key ON and you hear the purge solenoid click you most likely have a shorted control wire or bad computer driver...also if the purge valve is stuck open all the time the car will run poorly after you fill the gas tank because the fumes from the EVAP canister is causing the car to run RICH after being drawn into the intake manifold !!...I bet you don’t have 12 volts at the pink wire !!
Im betting im not getting 12v, cant hear it click when key is turned on. Maybe ill just go ahead and have it tuned out. Since im also having issues with the skip shift aswell.
Originally Posted by 2quick98 View Post
your cruise control switch is probabl striped , replace it and I bet you will have c/c
Whats stripped out on the cruise control? The set button?
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Old 05-18-2019, 07:00 PM
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Originally Posted by Empire087 View Post
Im betting im not getting 12v, cant hear it click when key is turned on. Maybe ill just go ahead and have it tuned out. Since im also having issues with the skip shift aswell.

Whats stripped out on the cruise control? The set button?
It’s part of the EVAP system and pretty sure you just can’t just “tune it out” !!...especially if you are in a state that does emissions testing !!...because it’s not “clicking” doesn’t mean you’re not getting 12 volts to the solenoid...just takes a little testing to make a correct diagnosis...and just some advise...whenever you get a DTC for a solenoid in your case, an O2 sensor, or whatever you ALWAYS have to check the wiring to that part...and sometimes it’s not even that part !!...a fuel delivery DTC like a failing fuel pump can cause an O2 sensor DTC.
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Old 05-19-2019, 04:04 PM
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Originally Posted by C5 Diag View Post
It’s part of the EVAP system and pretty sure you just can’t just “tune it out” !!...especially if you are in a state that does emissions testing !!...because it’s not “clicking” doesn’t mean you’re not getting 12 volts to the solenoid...just takes a little testing to make a correct diagnosis...and just some advise...whenever you get a DTC for a solenoid in your case, an O2 sensor, or whatever you ALWAYS have to check the wiring to that part...and sometimes it’s not even that part !!...a fuel delivery DTC like a failing fuel pump can cause an O2 sensor DTC.
Thankfully i live in a non emissions state, so that stuff doesnt cause me any issues. It can be tuned out with hp tuners, but id prefer to fix the issue first. I know why its there, thats why i want to correct it. Im also well aware of what you mean by one issue causing another, but i dont think it can apply to this unless there is an issue with the circuit all together. Short of having a major issue with the pcm, which i hope isnt the case. Thats why i was wondering if the skip shift and purge solenoid systems are tied together as it throws a code, and always has one pending aswell. It does this as soon as the get cleared using a code reader, and while using the dic. Short of trying to pull back the entire wiring harness(which is no small feet on a c5), i was trying to trouble shoot possible causes within the system short of a major wiring issue. Im going to pull the gauge cluster to make sure its not something as simple as the skip shift light on the gauge cluster being burned out.

The other thing is with the cruise control, short of wiring issues that just arent common, hoping to find others that had other issues which might point towards things to look at. Also is there any way to test the cruise control stalk to verify an issue with it? Instead of just throwing the parts cannon at it?
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Old 05-19-2019, 09:17 PM
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the switch has a threaded contact where it mounts . Over time the threads get buggered up and loose and becomes out of adjustment its a known problem .
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Old 05-19-2019, 09:44 PM
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Originally Posted by 2quick98 View Post
the switch has a threaded contact where it mounts . Over time the threads get buggered up and loose and becomes out of adjustment its a known problem .
Are you talking about the foot pedal switches or the stalk itself? Theres a switch on both the pedals for cruise control. Both area adjusted to be all the way tight, on top of that, unless they are all the way out they will make contact.
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Old 05-19-2019, 10:02 PM
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Originally Posted by Empire087 View Post
Thankfully i live in a non emissions state, so that stuff doesnt cause me any issues. It can be tuned out with hp tuners, but id prefer to fix the issue first. I know why its there, thats why i want to correct it. Im also well aware of what you mean by one issue causing another, but i dont think it can apply to this unless there is an issue with the circuit all together. Short of having a major issue with the pcm, which i hope isnt the case. Thats why i was wondering if the skip shift and purge solenoid systems are tied together as it throws a code, and always has one pending aswell. It does this as soon as the get cleared using a code reader, and while using the dic. Short of trying to pull back the entire wiring harness(which is no small feet on a c5), i was trying to trouble shoot possible causes within the system short of a major wiring issue. Im going to pull the gauge cluster to make sure its not something as simple as the skip shift light on the gauge cluster being burned out.

The other thing is with the cruise control, short of wiring issues that just arent common, hoping to find others that had other issues which might point towards things to look at. Also is there any way to test the cruise control stalk to verify an issue with it? Instead of just throwing the parts cannon at it?
Here is the schematic for the '98...like I said see if you have power to the purge solenoid and skip shift solenoid !!...you may be losing power to both !!...see if you have power to the pink wire at the MAF sensor key ON !!


Last edited by C5 Diag; 05-19-2019 at 11:59 PM.
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Old 05-19-2019, 10:55 PM
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CC wiring !!

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Old Yesterday, 10:28 PM
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Originally Posted by C5 Diag View Post



Here is the schematic for the '98...like I said see if you have power to the purge solenoid and skip shift solenoid !!...you may be losing power to both !!...see if you have power to the pink wire at the MAF sensor key ON !!

So i went and poked through my fuse box, and the 20 maxi fuse was gone, which will 100% cause the light. Drove it around for probably 15 miles and the light hasnt come back. Was shown as pending, but it may take a few key cycles to clear it. Cc fuses look good.
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Old Today, 05:06 PM
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So i guess at this point im not sure whats going on with the cruise control, The part that worries me the most that its mostly intermittent, as it did work for that short period of time. But it did work until i shut off the car.
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