Instrument cluster lights up but none of the gauges move

grcauto

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#32
If things start working with a scan tool hooked up and don't work when unhooked it'll be a ground issue to that module. The scan tool will provide the ground and allow the module to function. Not sure if this is a help if you don't have a scan tool suitable for the vehicle. I would get a good tool that will work with your vehicle and see if things start working. If so you know the ground to that module is bad.
If you can't find a tool to work with your Benz just start looking at the power and grounds to the effected modules.
 

Chaud

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#35
If things start working with a scan tool hooked up and don't work when unhooked it'll be a ground issue to that module. The scan tool will provide the ground and allow the module to function. Not sure if this is a help if you don't have a scan tool suitable for the vehicle. I would get a good tool that will work with your vehicle and see if things start working. If so you know the ground to that module is bad.
If you can't find a tool to work with your Benz just start looking at the power and grounds to the effected modules.
A good scan tool has the same problem as my Innova. Here is why? This vehicle has smog test due deadline by the end of this month. So today I took it to a smog station. After 5 minutes the technician told me there was no link established between the car computer and his OBD2 analyzer so he cannot run the smog tests. This I hope settles the question even a good professional OBD2 analyzer did not establish a link. My non-Mercedes Innova displays the same message...No link. By connecting any of the two analyzers did not make the needles work so it may not be module ground issue.
 

grcauto

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#36
Best bet is to start unplugging modules and see if you get comms to come up. You could have a bad module pulling the network down.
 

Chaud

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#37
Best bet is to start unplugging modules and see if you get comms to come up. You could have a bad module pulling the network down.
Good point. How do I unplug the modules? You mean pull out the instrument cluster and unplug one by one non working needles module such that only one module is unplugged at any time.
 

grcauto

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#38
Best thing is to unplug modules one at a time and check for comms after each one is disconnected. You don't want to just pull fuses for the modules because they can develop problems with the bus that will only free up the network by physically disconnecting the module.
In your case I believe you have a module for the instrument cluster. I would disconnect that module and see if comms come back. If so you know that module has a problem. Always start with the module(s) where you know you may be having problems. In your case the IPCM.
 

Chaud

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#39
Best thing is to unplug modules one at a time and check for comms after each one is disconnected. You don't want to just pull fuses for the modules because they can develop problems with the bus that will only free up the network by physically disconnecting the module.
In your case I believe you have a module for the instrument cluster. I would disconnect that module and see if comms come back. If so you know that module has a problem. Always start with the module(s) where you know you may be having problems. In your case the IPCM.
I have never dealt with these modules before so I don't know their locations. Are they behind the instrument cluster (dashboard w/gauges) or outside in the engine bay or some other place. Thanks
 

grcauto

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#40
I'm pretty sure it's behind the cluster in the IP. It may be integrated with the cluster. I think some earlier Benz were that way. Do you not have any service info on this vehicle?
 

Chaud

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#41
I'm pretty sure it's behind the cluster in the IP. It may be integrated with the cluster. I think some earlier Benz were that way. Do you not have any service info on this vehicle?
Ok, I know the location now but if it is all integrated it will be hard to know what is what. I don't have any service info on it.
 

grcauto

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#42
Pull the cluster and you'll see if it's integrated. If it is just unplug it from the cabling coming in. If not just follow the cabling to the module and unplug all connector at the module. Once the module is disconnected see if your can read the data line. I think you probably will.
 

Chaud

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#43
I am glad to be back and have an interesting observation to report. Ok the other day all gauges start working like normal while engine is running. So I immediately hooked up the analyzer to the OBD2 port to see if analyzer can communicate with ECU computer. It did and link was established. Once I stopped the engine and then restarted. All gauges were dead along with OBD2 port. What it tells me is that when computer is working it supplies it's output to gauges and OBD2 port. This rules out any soldering issue on the cluster pc board because if it was then cluster will be bad and OBD2 port working. But it is not so either both dead or both alive. So it leads me to believe either computer is dead or not getting power. The question is where this power terminal or pin is on a connector so that I could measure the voltage. Any thoughts on my assumptions or any suggestion I should try. Appreciate you help always. Chaud
 

grcauto

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#44
This tells me that there's a comm problem between the cluster and the rest of the network. When you have a network that has an issue where one of the modules is pulling the network down you start unplugging modules until the netowrk is back up. This will tell you what module is having the issue with the bus line. If the network is being interrupted due to a loss in the cluster because of a bad ground or solder joint this brings the network down. If that ground or bad solder joint happens to make connection again the network is back up the cluster is now working and your scan tool can communicate with the network. Pretty much confirms what I was saying. Unplug the cluster and your scan tool will communicate with the ECU. The cluster has a bad solder joint.
 

Chaud

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#45
grcauto, I am trying to understand what you said.."When you have a network that has an issue where one of the modules is pulling the network down...." This can only happen if at least one of the module is shorted out. If that is the case then ground is solid and not floating or disconnected. This contradicts with your statement of ground being open. Now if ground is open or making a weak contact due to cold solder then you cannot pull the node or network bus down because no current is flowing. Another contradiction to your statement. Your thoughts or anyone else comments will be appreciated.