Fault code 801C20 ZGM:central fault memory full-no control unit fault is store in ZGM (central gateway module) control module. There might be no electrical problem in vehicle even if this fault code is store in control module. But in some cases when there are so many electrical problem occurs in vehicle. This fault code is also store in control module along with that all the other fault codes.
Low voltage in vehicle could be the main reason behind this fault code to be store in control module. Check battery voltage with the help of multimeter. There should be 12 Volt or above present at ignition and 14.30 or above voltage after starting engine at idle speed.
When there is no any electrical problem in vehicle like central locking is working fine, music system and all the other system of interior are working fine. In that situation ignoring this fault code could be good as this is a normal fault code to store in control module.
Sometime this fault code could be store in control module after replacing old battery with new battery. Also when battery get drain due to any reason this fault code can be store in control module. To remove this fault code you need to do coding of new battery.
Causes of 801C20 ZGM:central fault memory full-no control unit fault:
After replacing battery.
Failure of any other control module.
Damage wiring harness of control module.
Blown fuse of control module.
Failure of any one part of music system.
Symptoms of 801C20 ZGM:central fault memory full-no control unit fault:
Music system may not work.
Central locking system does not work properly.
Air conditioning system may stop working.
Any other problem in comfort system in vehicle.
Some other control module may stop functioning.
how to trouble shoot:
There might be so many reason due to which this fault code is store in control module. All the reason of this fault code are listed below.
1# Low battery voltage: This is the very first reasons behind this fault code to be store in control module. Check battery voltage if it is below 12V than recharge the battery. Also check battery condition, because after some year battery get weak which require to change. Due to low battery power control module did not get enough voltage to function properly. In this situation either charge battery to it full capacity or change battery so than control module can recieve require amount of voltage. When voltage flow will be according to the requirement of control module. Than it could be possible that this fault code can not be store in control module. Sometime after replacing old battery with new battery, it is necessary to do coding of battery.
2# Blown fuse: check fuse at fuse box which are at left side behind glow box. There is a fuse which is known as ACC fuse check this fuse,if fuse is blown than replace that blown fuse. Because this fuse is use to supply power to most of the control module when ignition is turn ON. When this fuse will blow up, it will stop sending ignition power supply to all the control module. In this situation this fault could be store in control module.
3# damage wiring harness: there are so many types of wire could be seen at the connector of all control module. which is use to supply power, ground, ignition voltage,signal wire, CAN wire, etc. All these things a control module need to function properly. When any one from these wire get damage or break than it might be possible that this control module stop functioning properly. so this is also a reason behind this fault code to be store in control module.
4# Faulty control module: there are so many control modules are present in the vehicle to control different type of comfort system. All of them are connected to each other with the help of CAN line wire to communicate each other. Because all of them are do communication with each other to perform different function to complete the requirement of driver comfort system. When anyone control module get fail due to any reason like blown fuse, damage wiring harness or anything than that perticular control module stop communicating with other control module. like this, there could be a problem can be happen with ZGM control module due any reason than this fault code could be store in control module.
5# Electrical problem in comfort system: when there is any problem at comfort system of vehicle like centre locking is not working, power window does not work, headlight does not turn ON, music system does not work. When this kind of problem will be there in vehicle than also this fault code will store in control module. But this means does not that there is a problem of faulty ZGM control module. Check fault code if that perticular control module which is not functioning. like if center locking system does not work than go to check CAS control module. There you will find fault code regarding why center locking system is not working. Check that fault code which is store in control module and solve that first.
Comman mistake while trouble shooting:
when this fault code is store in control module, technician start working on this fault code which is not necessary. First thing they need to do is to check that which system is not working than according to that check fault code of that control module which is use to control that system. By not doing this thing they directly start working on this fault code and at the end they give up by not solving this fault code.
Note:
When there is no any electrical problem in vehicle and all the comfort system working fine. Than this fault code can be ignored as this is not troubling any thing. But if there is some problem at comfort system or at centre locking system then this fault code can be take as serious. Most of the time this fault code store due to low battery power. That’s why you need to check problem at battery like battery power, battery life etc.
In other case like no communication with any control module, like with ZGM, air bag, ICM, Ac control you need to work on CAN line if there is any fault code store in conntrol module regarding about CAN line failure.