No AC fans and the ignition protection relay

I was asked to assist in determining why the climate control fans suddenly stopped working on a Series 2 xj6. My efforts were remote to the car and via phone.

We went down the usual path of testing fans and checking for power on the fan relay pack. All checked fine and determined the issue was no power to the low amperage control side.

All fuses checked fine…but as we dug a bit further…we found no power coming into the fuse block ignition switched AC lines.

We suspected a faulty ignition switch since we were getting no power to the fuse block. As the detailed wiring diagrams in the manual came out…we found the existence to the " ignition protection relay" . apparently this relay is mounted behind the dash facia and gauges and is switched via the ignition switch and controls AC and windshield wipers.

When my friend went to do the hands on testing…he confirmed his windscreen wipers indeed did not function. Upon removal of the dash facia…he found one of the leads from the ignition protection relay had come loose.

After a clean up and reinstallation…power was returned to supply the switched circuits in the fuse block and everything began working again.

Can anyone offer any clarity of what years and models have this “ignition protection relay”? Xj6 series 2 and 3? XJS models?

I never had reason to dig this far into the AC circuit…and was surprised by this relay…I never stop learning.

Cheers

Gary

Series 3 has it and mine failed so I changed it in a parking lot abroad. Its purpose should be to take the load off the ignition switch.

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Early SII cars had them as well.

Unswitched power going in on a brown wire at C2 and a switched white/pink wire going in from the ignition switch at W1. C1 supplies the heated backlight by a white/black wire via fuse #12, and the AC heater circuit as well as the windscreen wiper by a light green wire via fuse #11. W2 is to ground. No further info as to the operation of the relay. My assumption would be that the “w-circuit” is the operating circuit. If ignition is on the relay will turn the operated “c-circuit” on as well. If either the white/pink wire loses contact at the ignition switch or the relay breaks, you lose heated backlight, AC/heater and window wipers.

Only if all three systems fail simutaneously and both fuses (in main fuse box) are operative, there is a need to dig out the ignition protection relay.

Good luck

Jochen

75 XJ6L 4.2 auto (UK spec)

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Gary,
Our 1990 prefacelift XJ-S also has the ignition protection relay and I believe the earlier XJ-Ss have it as well. I don’t know much about the face-lift cars (1992-1996) and I have no idea whether or not they have an ignition protection relay.

Paul

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**
The ignition protection relay is listed in my wiring diagrams on all ‘series’ cars, Gary - but what was powered through it
during the years may differ…?

The purpose of it is just to avoid high power components being powered through the ignition switch - protecting it from high currents. The proper name should really be the ‘ignition switch protection relay’…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
**

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