Radio fail + Aerial fail + Blower fail + Heating fail

XJ40
1

Hi all,

I own a late 1990 4.0 sovereign. I don’t use it much, and some problems appeared to me after the car sat outside for 3 month at a workshop. I think the problems might be related

  • Radio won’t turn on, no light, no code asked
  • Aerial stays up
  • Blower fan not working except on “Max”
  • Heating not working
  • Boot button not working, only electrical release from the inside working. This might be a mechanical problem…
  • VCM says Fuse 5 / 6 fail

Can all this be related to the battery ?

2

Jean, welcome to Jag-lovers. Given the car sat outside, and the problems are electrical in nature, I would suspect water ingress. Any sign of dampness in the right side front carpet / floorboard? There is an AC/radio relay (black base) beneath the dash / glove box (left hand drive vehicles). Unplug that relay and check for any signs of water damage.

3

If you suspect the battery is faulty or not fully charged you should rectify this before looking any further. If the battery was already old then standing unused for over three months has probably killed it completely. A poor battery on an XJ40 can cause a whole range of seemingly unconnected issues and without changing it for a known good one trying to trouble shoot electrical problems is a waste of time. Also clean all the earthing points you can find around the car, particularly those on the bulkhead because poor ground connections will also cause all kinds of electrical problems.

4

Yes, batteries are critical in these cars and the parasitic draw will kill them over time unless kept on a battery maintainer.

5

By the way, I did not comment on the fuse 5 and 6 failures in my previous post. Here is a link to some information about that supplied by our fellow Jag-lover Bryan N:

[xj40] anti lock lights again - #2 by Bryan_N?

6

Jean,

I concur with all responses regarding battery health. My '99 X308 (XJ-R) lives off its battery. If I let the car sit for even a couple of weeks certain circuits in the car will slowly drain the battery. You don’t give a location so worst case: South - battery life usually around 3-4 years. Northern USA, 4-5 years. A low performing battery, even if it tested OK, may cause many of the electronics woes. I’d start with replacing the battery if it’s over 4 years old. The type (open cell, sealed, etc.) is your option.
With a new battery installed power up the car and let it “adjust” for a few minutes before proceeding to crank, test components, etc. Hopefully, a new battery will be a quick fix!

Happy Trails,

Dick

7

Hi all

I am from France so the weather is sometimes cold. I had to charge the battery several times and it is from 2019 so I think it is dead.

The blower fan came back but still no hot air.

Thank you very much, I will tell you tomorrow how it turned out !

8

Quick update :

When I remove the radio fuse or the green radio relay behind the glovebox, the heater fan stops working. How these two can be related ?

No water damages inside the car.

9

Both fuses look OK, and I have no warning on the dashboard.

10

Hi all,

I changed the battery yesterday. The radio did not came back but I guess it won’t harm. What are the other possibilities ?

11

Have you checked the footwell fuse boxes?
They are known failure points due to cracked (cold) solder joints. Search the site for more info and remedies.