So because I am still kind of new to the whole "security" of the XJS, I had been looking at another one to replace the white one, that recently decided to throw a rod bearing / oil pump.

Took a charged battery to the car, hooked it up, radio (stock) demanded a security code be entered.

Will this also prevent the car from being started?

We put the key in and everything worked (Headlights, turn signals, 4-ways, even heard the fuel pump for the split second) but it would not turn over. I wasn't sure if I needed to clean the starter terminals or if it's something to do with the security system and that 4 digit code....

I am planning on picking the girl up this coming weekend and just wanted to know what I might be up against. It too is an 89.... Pre-Facelift/FORD.

 

Radio code has nothing to do with the cars security system (if your '89 has one). But will be needed if you want to listen to the radio though.....

 

Like Malc4d said, the radio code is just to deter theft by making the radio unusable for the guy that stole it. That doesn't mean that the alarm system isn't preventing the car from starting though. I don't know from personal experience but I've read several stories here about security system problems triggered by dead batteries.