When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
2008 saturn astra gauge cluster not lighting up and code U0073
hello saturn community, i recently purchased a 2008 saturn astra xr with a 1.8L and automatic transmission. the car runs and drives perfectly but it’s having some electrical problems. i noticed my gauge cluster was not lighting up when driving at night. i checked the dimmer switch and nothing happened when i turned the ****. also checked the actual headlight switch to see if my headlights were on. i put the **** in the automatic, off and on position again nothing happened. doesn’t matter what position i put the headlight switch in the headlights stay on even in the off position. i’ve replaced the headlights switch again same issue. i noticed a green light was on below the rpm gauge, the light is a headlamps sign with a line crossed through it. in the owners manual it says this sign is for “exterior lamps off reminder”. that sign is a reminder that the headlights are off, but my headlights are stuck on even during the daytime. i also checked the fuse for the cluster and it’s not blown. what really surprised me was when i turn the ignition off and pull the key out the gauge cluster lights up and turns off automatically after time. the cluster lights up and gets power but not while the car is running. also the obd scanner is showing code u0073 “control module communication bus off”. i have no idea what this code could be. in conclusion the gauge cluster won’t light up when the cars running. the exterior lamps off reminder sign is on but the headlights are stuck in the on position. the headlight switch does not work, and can’t control the headlights. and code u0073 is showing up. any help would be much appreciated thank you ^ this is the light that is on the dash
There must be a communications module in the dash/cluster that talks to the body control module which is where most of the stuff on the interior of the car is centrally controlled. Similarly, there is a communications module in the transmission, one for the engine, another for the HVAC, and so on and so on. When one of those modules stops communicating, It doesn't receive signals that are being sent out to it to do things like turn on the cluster lights, turn off the headlights etc.
The fact that the cluster lights come on when you take the key out makes it sound like the ignition module is somehow involved. Or should I say that detection of the key being present is involved. What sucks is that you cannot read the codes with the key out unless you can find a way to put the car in run without using the key which I don't recommend unless you truly know what you're doing. Even if you subdied 12 volts to your OBD II MX+, I don't think anything else would have the power to have the computer awake for you to read the codes.
To be clear, after you remove the key, does the headlight switch work properly for example? Or the dimmer switch when the dash lights are on with the key out?
Unfortunately we don't have an Astra specialist right now. Actually not ever but we will try to help you solve your issue cuz that's just what we do on this forum. Have you looked for TSBs on your vehicle? Also, how soon did this show up after you purchased the vehicle? Communications failures generally do not just suddenly occur. Meaning to previous owner May have known but cleared the codes before you test drive it, etc.
There must be a communications module in the dash/cluster that talks to the body control module which is where most of the stuff on the interior of the car is centrally controlled. Similarly, there is a communications module in the transmission, one for the engine, another for the HVAC, and so on and so on. When one of those modules stops communicating, It doesn't receive signals that are being sent out to it to do things like turn on the cluster lights, turn off the headlights etc.
The fact that the cluster lights come on when you take the key out makes it sound like the ignition module is somehow involved. Or should I say that detection of the key being present is involved. What sucks is that you cannot read the codes with the key out unless you can find a way to put the car in run without using the key which I don't recommend unless you truly know what you're doing. Even if you subdied 12 volts to your OBD II MX+, I don't think anything else would have the power to have the computer awake for you to read the codes.
To be clear, after you remove the key, does the headlight switch work properly for example? Or the dimmer switch when the dash lights are on with the key out?
Unfortunately we don't have an Astra specialist right now. Actually not ever but we will try to help you solve your issue cuz that's just what we do on this forum. Have you looked for TSBs on your vehicle? Also, how soon did this show up after you purchased the vehicle? Communications failures generally do not just suddenly occur. Meaning to previous owner May have known but cleared the codes before you test drive it, etc.
someone on a different saturn forum said this car does not have a body control module. instead it has a similar communication interface module or some people call it “onstar”. i located that on the left side under the dash. i forgot to mention this before but sometimes while driving all of my dash lights(battery, abs, engine light) start flickering uncontrollably. when i unplugged the onstar all of my dash lights turned on similar to the symptom i had while driving. i’ll try to see if the headlight switch works with key out. thanks for reply
There must be a communications module in the dash/cluster that talks to the body control module which is where most of the stuff on the interior of the car is centrally controlled. Similarly, there is a communications module in the transmission, one for the engine, another for the HVAC, and so on and so on. When one of those modules stops communicating, It doesn't receive signals that are being sent out to it to do things like turn on the cluster lights, turn off the headlights etc.
The fact that the cluster lights come on when you take the key out makes it sound like the ignition module is somehow involved. Or should I say that detection of the key being present is involved. What sucks is that you cannot read the codes with the key out unless you can find a way to put the car in run without using the key which I don't recommend unless you truly know what you're doing. Even if you subdied 12 volts to your OBD II MX+, I don't think anything else would have the power to have the computer awake for you to read the codes.
To be clear, after you remove the key, does the headlight switch work properly for example? Or the dimmer switch when the dash lights are on with the key out?
Unfortunately we don't have an Astra specialist right now. Actually not ever but we will try to help you solve your issue cuz that's just what we do on this forum. Have you looked for TSBs on your vehicle? Also, how soon did this show up after you purchased the vehicle? Communications failures generally do not just suddenly occur. Meaning to previous owner May have known but cleared the codes before you test drive it, etc.
thanks for your reply!!! i was reading on another saturn forum and they said the astra does not have a body control module. it has a similar communication interface module (CIM) or onstar as some refer to it as. i’m not 100% sure but there’s a module behind the dash on the drivers side way up there to the left. this could potentially be the CIM. i forgot to mention this before but while driving the dash warning lights randomly start flickering sometimes. i was playing around with the wires on the mysterious module behind the driver side dash and when i pulled the power wire out the cluster warning lights like abs, check engine, traction control started flickering exactly the same way as i experienced then the day before while driving. i will test to see if headlights work when key is out as you suggested. does anyone know where the modules actually are? like the ignition and body control?
There must be a communications module in the dash/cluster that talks to the body control module which is where most of the stuff on the interior of the car is centrally controlled. Similarly, there is a communications module in the transmission, one for the engine, another for the HVAC, and so on and so on. When one of those modules stops communicating, It doesn't receive signals that are being sent out to it to do things like turn on the cluster lights, turn off the headlights etc.
The fact that the cluster lights come on when you take the key out makes it sound like the ignition module is somehow involved. Or should I say that detection of the key being present is involved. What sucks is that you cannot read the codes with the key out unless you can find a way to put the car in run without using the key which I don't recommend unless you truly know what you're doing. Even if you subdied 12 volts to your OBD II MX+, I don't think anything else would have the power to have the computer awake for you to read the codes.
To be clear, after you remove the key, does the headlight switch work properly for example? Or the dimmer switch when the dash lights are on with the key out?
Unfortunately we don't have an Astra specialist right now. Actually not ever but we will try to help you solve your issue cuz that's just what we do on this forum. Have you looked for TSBs on your vehicle? Also, how soon did this show up after you purchased the vehicle? Communications failures generally do not just suddenly occur. Meaning to previous owner May have known but cleared the codes before you test drive it, etc.
thanks for your reply!!! i was reading on another saturn forum and they said the astra does not have a body control module. it has a similar communication interface module (CIM) or onstar as some refer to it as. i’m not 100% sure but there’s a module behind the dash on the drivers side way up there to the left. this could potentially be the CIM. i forgot to mention this before but while driving the dash warning lights randomly start flickering sometimes. i was playing around with the wires on the mysterious module behind the driver side dash and when i pulled the power wire out the cluster warning lights like abs, check engine, traction control started flickering exactly the same way as i experienced then the day before while driving. i will test to see if headlights work when key is out as you suggested. does anyone know where the modules actually are? like the ignition and body control?
There must be a communications module in the dash/cluster that talks to the body control module which is where most of the stuff on the interior of the car is centrally controlled. Similarly, there is a communications module in the transmission, one for the engine, another for the HVAC, and so on and so on. When one of those modules stops communicating, It doesn't receive signals that are being sent out to it to do things like turn on the cluster lights, turn off the headlights etc.
The fact that the cluster lights come on when you take the key out makes it sound like the ignition module is somehow involved. Or should I say that detection of the key being present is involved. What sucks is that you cannot read the codes with the key out unless you can find a way to put the car in run without using the key which I don't recommend unless you truly know what you're doing. Even if you subdied 12 volts to your OBD II MX+, I don't think anything else would have the power to have the computer awake for you to read the codes.
To be clear, after you remove the key, does the headlight switch work properly for example? Or the dimmer switch when the dash lights are on with the key out?
Unfortunately we don't have an Astra specialist right now. Actually not ever but we will try to help you solve your issue cuz that's just what we do on this forum. Have you looked for TSBs on your vehicle? Also, how soon did this show up after you purchased the vehicle? Communications failures generally do not just suddenly occur. Meaning to previous owner May have known but cleared the codes before you test drive it, etc.
thanks for your reply!!! i was reading on another saturn forum and they said the astra does not have a body control module. it has a similar communication interface module (CIM) or onstar as some refer to it as. i’m not 100% sure but there’s a module behind the dash on the drivers side way up there to the left. this could potentially be the CIM. i forgot to mention this before but while driving the dash warning lights randomly start flickering sometimes. i was playing around with the wires on the mysterious module behind the driver side dash and when i pulled the power wire out the cluster warning lights like abs, check engine, traction control started flickering exactly the same way as i experienced then the day before while driving. i will test to see if headlights work when key is out as you suggested. does anyone know where the modules actually are? like the ignition and body control?
do you know where i can find the modules on this car???
thanks for your reply!!! i was reading on another saturn forum and they said the astra does not have a body control module. it has a similar communication interface module (CIM) or onstar as some refer to it as. i’m not 100% sure but there’s a module behind the dash on the drivers side way up there to the left. this could potentially be the CIM. i forgot to mention this before but while driving the dash warning lights randomly start flickering sometimes. i was playing around with the wires on the mysterious module behind the driver side dash and when i pulled the power wire out the cluster warning lights like abs, check engine, traction control started flickering exactly the same way as i experienced then the day before while driving. i will test to see if headlights work when key is out as you suggested. does anyone know where the modules actually are? like the ignition and body control?
thanks for your reply!!! i was reading on another saturn forum and they said the astra does not have a body control module. it has a similar communication interface module (CIM) or onstar as some refer to it as. i’m not 100% sure but there’s a module behind the dash on the drivers side way up there to the left. this could potentially be the CIM. i forgot to mention this before but while driving the dash warning lights randomly start flickering sometimes. i was playing around with the wires on the mysterious module behind the driver side dash and when i pulled the power wire out the cluster warning lights like abs, check engine, traction control started flickering exactly the same way as i experienced then the day before while driving. i will test to see if headlights work when key is out as you suggested. does anyone know where the modules actually are? like the ignition and body control?
Originally Posted by derf
There must be a communications module in the dash/cluster that talks to the body control module which is where most of the stuff on the interior of the car is centrally controlled. Similarly, there is a communications module in the transmission, one for the engine, another for the HVAC, and so on and so on. When one of those modules stops communicating, It doesn't receive signals that are being sent out to it to do things like turn on the cluster lights, turn off the headlights etc.
The fact that the cluster lights come on when you take the key out makes it sound like the ignition module is somehow involved. Or should I say that detection of the key being present is involved. What sucks is that you cannot read the codes with the key out unless you can find a way to put the car in run without using the key which I don't recommend unless you truly know what you're doing. Even if you subdied 12 volts to your OBD II MX+, I don't think anything else would have the power to have the computer awake for you to read the codes.
To be clear, after you remove the key, does the headlight switch work properly for example? Or the dimmer switch when the dash lights are on with the key out?
Unfortunately we don't have an Astra specialist right now. Actually not ever but we will try to help you solve your issue cuz that's just what we do on this forum. Have you looked for TSBs on your vehicle? Also, how soon did this show up after you purchased the vehicle? Communications failures generally do not just suddenly occur. Meaning to previous owner May have known but cleared the codes before you test drive it, etc.
where can the modules be located. the car was like this when i bought it
01-23-2023, 09:04 PM
2008 saturn astra gauge cluster not lighting up and code U0073
