Radio issue no power 1991 sov 4.0

anyone know what happens when reverse voltage is sent to ignition when in assy position knocked out radio in my case

I know when I reversed the polarity in my ‘92 it knocked out the ECU, hope yours has survived.

i think so radio an anntena function gone i read somewhere that there may be an issue eith the pass side fuse panel where the fuse checks good but the back of the panel itself isnt have taken it off to check yet i cant sing so i listen to the wine i kinda like that sound thou

reminds me of a 56 chev bel air that i got from my dad in 65

The ECU is supposed to be protected by a relay that has a diode preventing its energizing if the battery is connected backwards. At least on the 80’s models; hard to believe they’d delete that particular protection for later models.

Reverse polarity is likely to knock out any connected up electronics, Arland - like if a battery is connected the wrong way…

Ie with ign ‘off’; nominally nothing is powered - except radio ‘stand-by’ power; constantly connected to battery. Which likely will knock out the radio, but effects on other items depends on how they are connected - and the position of the ign switch…

Certainly, modern electronics usually have built in protection against reverse polarity, but older items may not. However; your radio might just have blown in internal fuse - fitted for that purpose…?

xj6 85 Sov Europe (UK/NZ)

thank you for the replies to the radio power issue that my 91 kj6 4.0 is having my more concerning problem is the trans fault after getting wet after washing i did dry it and drained the heater housing looked like that has had water in it for quite a while well the fault was removed and all looked good until i drove it down my driveway that lite was back on before i could get on the road so thats where that is back in garage ecu harness was wet should be dry i sprayed a lot of wd 40 on both the ecu harness as well as the trans management computer those two connections didnt appear to have suffered as much as the ecu althou from what i can tell have a direct connection to the ecu which would put it at risk im going to dry them some more and remove the wd 40 residue do you or have you had any luck with reserecting these units thanking you in advance for any input to this issue its summertime stay safe and have a good day !!!