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| Thread ID: 100036 | 2009-05-23 23:19:00 | Car radio question | tut (12033) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 776296 | 2009-05-23 23:19:00 | I have an old Mitzi Magna wagon used as a runabout. It was off the road for a couple of months and now back in action. Now when I turn off the key the radio loses all its presets. Doesnt happen if I just turn off the radio with the key on. Just curious about this but what holds the presets when the power is taken off the radio. I have never seen a back up battery in a car radio so if not it must be getting power from somewhere. |
tut (12033) | ||
| 776297 | 2009-05-24 00:07:00 | It sounds like the connection for the standby/memory power has broken. Most radios have two cables for power, one connected to the battery for the memory and one to the ignition so that it will only work when the key is turned on. It's been a while since I worked on a car radio but from memory most of them have a yellow cable for the battery/memory power and it should have a fuse in line on this cable as well. |
CYaBro (73) | ||
| 776298 | 2009-05-24 03:59:00 | You can sometimes lose the "Keep-alive memory" from radio and even the ECM adaptive strategies in your vehicle's computer system if the battery voltage falls below a preset value. If, for instance, you have a battery that is on the bleeding edge of going belly-up and you ask the starter to draw from that - it leaves very little for the electrical system for maintenance. In other words: it dumps the memory. Ford vehicles are notorious for damaging their transmission if the "KAM" loses electrical connectivity and you dump all the adaptive values that the ECM has established for the transmission, and if you don't get a parity sync very quickly, you smoke the transmission. |
SurferJoe46 (51) | ||
| 776299 | 2009-05-24 04:41:00 | It sounds like the connection for the standby/memory power has broken. Most radios have two cables for power, one connected to the battery for the memory and one to the ignition so that it will only work when the key is turned on. It's been a while since I worked on a car radio but from memory most of them have a yellow cable for the battery/memory power and it should have a fuse in line on this cable as well. Cyabro has nit the nail on the head it has lost the battery connection due to fuse, bad connection, break in continuity of the feed wire. Failing that the radio has an internal fault easily fixed by throwing the radio away and buying another one. One way to test it is get a 9v battery and a ciggy lighter male and plug it in and turn key off station memory will be saved. |
prefect (6291) | ||
| 776300 | 2009-05-24 04:50:00 | Cyabro has nit the nail on the head it has lost the battery connection due to fuse, bad connection, break in continuity of the feed wire . Failing that the radio has an internal fault easily fixed by throwing the radio away and buying another one . One way to test it is get a 9v battery and a ciggy lighter male and plug it in and turn key off station memory will be saved . Nine volts is just on the cusp of dumping the settings, so if you inadvertently open the door and the interior lights go on, the memory is still lunched . This won't be a valid test for the KAM of the radio either . After all - you have that big 12 volt device under the hood feeding the same circuits anyway . The only real purpose for the power-port trick and the nine-volt battery is when you have to disconnect the starting battery from the vehicle - say, to replace it - and you don't want to have an unhappy customer throwing a tantrum since you deleted his favorite stations . But if you put a demand on the nine-volt battery for ANYTHING that requires even 1/4 amp of so, you lose everything anyway . Nine-volt batteries cannot start the engine nor operate any automotive devices - they ain't got the amps! ANYTHING includes: interior lights horn ignition ON brake lights four-way flashers etc etc |
SurferJoe46 (51) | ||
| 776301 | 2009-05-24 05:06:00 | Its just used as a test. Step 1 start engine Step2 put presets in radio Step3 put in 9v ciggie tool (as the yank said dont open the door or turn anything on) Step4 turn off car Step 5 turn key back on are presets kept? |
prefect (6291) | ||
| 776302 | 2009-05-24 11:33:00 | Blimey surfer joe. Thats a bit technical. This is some old shitbox mitsibishi. Check the fuses if it's been off the road, assuming nothing happend to it while it was off the road | Phil B (648) | ||
| 776303 | 2009-05-24 19:55:00 | If it has been off the road for a while then someone would have been working on the car battery, either replacing it or disconnecting it to recharge. When the radio was installed (if done by amateur) then they could have run the battery wire - literally to the battery. This could have been dislodged when the battery was worked on. Check around the positive battery terminal to see if there are any loose or disconnected wires. | sam m (517) | ||
| 776304 | 2009-05-24 23:23:00 | Blimey surfer joe. Thats a bit technical. This is some old shitbox mitsibishi. Check the fuses if it's been off the road, assuming nothing happend to it while it was off the road C'mon! Fuses don't get old and die like milk or eggs. If they haven't been used by being off road, then the chances of them being bad are even more remote. If "off road" in NZ-Speak means that it was driven (off road) and maybe rolled a few times, dropped off a few tectonic plates and through a volcano or into a steam vent, struck by lightning and/or used for target practice, then I will retract my statement. The KAM for the radio is what seems to be the problem and putting a 9-volt battery in the same receptacle that the BIGGER vehicle battery is also keeping hot is NOT a test of the KAM, the fuses or the radio. The only thing to do is make sure that the KAM wire to the radio is hot all the time - even when the ignition is OFF. The purpose of the KAM is in it's name: "Keep Alive Memory" and it needs some source of voltage to keep the presets in the radio during times when the engine's not running by the vehicle battery being allowed to do so by a small, insignificant wire that goes to the KAM. This is NOT rocket surgery! A nine-volt battery in the lighter socket is NOT the right way to test the radio KAM. For sake of argument: there is a KAM in most ECM/VCMs too for the sake of the vehicle's adaptive driveability factor. Many times there will be an "A" and a "B" fuse for the ECM/VCM - one for times when the engine's OFF and the other for when the engine's ON. |
SurferJoe46 (51) | ||
| 776305 | 2009-05-25 01:32:00 | You must have strange cars in usa we are only talking shitbox mitsi here. Unlike your country we can buy readymade 9v ciggy lighter tools at Repco/Supercheap Auto just for things like this although a Kiwi bloke will make his own from stuff bought at DSE but you probaly dont have DSE in usa. But unfortunaly you probably dont have Supercheap auto or Repco in usa. Its not rocket science the radio is losing its battery power there is no KAM not sure about usa but radios here come with 2 power wires. One live other from ignition ie you turn the key to get power. |
prefect (6291) | ||
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