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I have owned 93 XJS coupe since 2013. Always had a daily voltage drain on the battery. Took to 2 local Jaguar tech repair shops. Answer: parasitic wiring. Use a battery maintainer. I did not accept the excuse of parasitic wiring. Put a battery maintainer on the battery.. Been like this for 5 years. So, yesterday a friend with knowledge on European cars helped track down the gremlin. We pulled every fuse (one at a time) from the LH and RH fuse boxes. We checked relays. Results - revealed gremlin was RH blower fan assembly control module.
This defective (or worn out from being an original piece) causes the fan motor module to continually run in the low speed setting. You cannot hear it running, but it does. This unit is a part of the blower assembly (CCC 5544)..I am looking for the piece shown. A replacement used CCC 5544 is about $165 + s/h. Only need the shown piece. This saga has lasted over 9 years. I have gone through 8 batteries and 2 alternators. The fuse #3 (20a) is in the RH fuse box. It has been removed. After working on this yesterday a battery read was 12.34. with fuse out. Today , the battery read 12.36 with fuse out. Gremlin has left the building. I hope...
Just a standard 2N3055 or 2N3772 similar spec transistor . Try to clean off the transistor an try to read the P/N. These are common transistors. I just replaced one on my 88 BMW 635Csi heater blower fan transistor. Similar circuit for variable fan speed. Full speed bypasses this curcuit so I had full speed fan but not variable.
My friend has ordered all the components,(with upgrades) to repair the shown panel. When they arrive, I will take my Jaguar to him for repair. The battery reading today was 12.34 with fuse out. My friend is writing an essay on this subject. Once completed, will try to post. One of the local Jag techs now agrees the drain was 'probably' the fan blower. Not parasitic, go figure. ..
My friend has ordered all the components,(with upgrades) to repair the shown panel. When they arrive, I will take my Jaguar to him for repair. The battery reading today was 12.34 with fuse out. My friend is writing an essay on this subject. Once completed, will try to post. One of the local Jag techs now agrees the drain was 'probably' the fan blower. Not parasitic, go figure. ..
Giving him the benefit of the doubt for a minute, maybe he meant "parasitic drain" as in it's not supposed to be there with everything off and it needs to be found as in its not normal to have and something unknown is causing it. Trunk light on when it's not supposed to be on is parasitic drain ...until you finally find it. Maybe all semantics. Just trying to get into his head. Glad you found it.
Then there is a "keep alive" drain which should be very small and usually supplies a memory circuit such as in a stereo head unit for stations. That drain is typically in the milliamps and is an acceptable drain not to kill a battery overnight or even in a week.. Your blower was probably drawing an amp or more if it was spinning a motor which is an inductive load.
Yep my right blower was my 93's parasitic draw problem too! I just took out the fuse for now. Hopefully I'll have the time to pull the assembly and fix it before too long. Oh and mines close to yours as the VIN is 188097!
Last edited by Timeisrelative; Apr 24, 2020 at 10:58 PM.
Way back in the 'Mists of Time' when I first joined the Forum, since I only used my Car on nice hot Summer days I often found my Battery had run down, which may have been caused by the Car Alarm that was always listening out for a signal as well as things like the Clock
Though most of all I think that lack of use was more to do with this than anything
At which point the GF came to the rescue and bought me a little gadget that was called a Car-Discarnect (or something like that) which are now all over ebay for under £5 and has to be one of the best things that I have ever fitted on my Car
As I never ever use a Battery Tender and I can leave the Battery in the Car all Winter and then when Summer arrives She Starts on the Button
The only thing I don't like about the battery disconnects is that you loose all my radio presets, and also the car seems to run a little funny until the computer relearns some of the settings.
Jaguar XJS (vin- 187xxx) ELECTRIC battery drain
