I have a 2008 Chevy Cobalt (piece of crap). I I have a 2008 Chevy Cobalt (piece of crap). I loved it at first but now I absolutely hate it. For a couple months now it has been going nuts. It will start dinging and all the gauge needles including mph, gas, and rpm flick up and down randomly and every malfunction possible pops up on the in-dash screen. Also does not show outside temp anymore or tire pressure shows up as lines instead of numbers. Also when this happens the transmission shifts VERY hard and is very scary to drive. I've had my mom drive it a few times to show her the problem and she claims she lost power steering as well. This has never happened to me. Also my a/c stops working when this happens and blows out hot outside air. I've had the power steering part replaced from the recall but it's never acted up until recently. I'm so very sick of every place I take it to telling me they can't figure out whats wrong with it. I haven't been able to drive my own car for 2 months because of this problem. I spend $750 on a power steering module being sworn by the mechanics that that was the problem but a few days later, what do ya know, back to craziness. I want to trade it off so bad but I'm afraid the dealership won't give me anything for it because of this. The car's worth at least $5,000 on a trade in without this problem. I've seen multiple people conplaining about this very same thing online but nobody seems to have any solutions. Just trial and error and more of your money by mechanics that have no idea what they're doing. If this is a simple fix that these people are simply missing I would be so grateful to know.

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28 Feb, 2017

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Have you had all the moduels check for code's ? Not autozone or anywhere else like that . Need professional type . Could have a GMLAN serial data network problem . All the control modules on the vehicle , PCM/ECM , BCM , instrument cluster , radio , air bag's , ABS , electric power steering etc... all share information on the data network . GMLAN is GM'S version of C.A.N. - controller area network . How to Diagnose Controller Area Network CAN Checking for communication problem codes is the first thing to do with problems like you are having . Have you taken it to a Chevy dealer ? This does sound like a data network problem .

The communication among control modules is performed through the GMLAN high speed serial data circuit and the GMLAN low speed serial data circuit. The modules that need real time communication are attached to the high speed GMLAN network. The body control module (BCM) is the gateway between the networks. The purpose of the gateway is to translate serial data messages between the GMLAN high speed buss and the GMLAN low speed buss. The gateway will interact with each network according to that network's transmission protocol. Refer to Body Control System Description and Operation for more information about the gateway.
The powertrain control module (PCM) on this vehicle, uses a class 2 serial data buss. The class 2 buss is only used for diagnostics and the service programming system (SPS). During normal vehicle operations, there is no communications over the class 2 serial data buss. Normal vehicle operational messaging for the PCM is sent over the PCMs GMLAN high speed serial data buss.

Could be a simple fix , i see them all the time . Lose ground wire for one of the modules . That includes the instrument cluster , it also has a microprocessor inside an can set DTC'S -diagnostic trouble codes . Finding a U code in one of the modules would shorten diagnostic time .
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