Hi guys, new here and new to Jags. Rookie..
I bought xj40 1988 few months back. Have spent time restoring and fixing inside out. She has been running and starting without any hick ups, until i took the airfilter off. Now engine doesnt turn, starter motor .akes no sound, when i turn the key there is nothing.

I can't figure out where those two(pictured) plugs were pulled from. I have a feeling it has something to do with that..



I cant find and remember anything that i took off from the unit.. please help. Thanks in advance.

 

First off- ive never had an 88 and they are somewhat different than the later cars. However, those plugs don't look like they've been plugged in. There is dirt in the terminals where the male plug would have blocked it (I think they are for an alarm system). On the later cars there are no electrics on the air box, but the maf sensor is next upstream, it has a wide flat plug but that wouldnt completely kill the car. Also on the later cars there are relays mounted near that area and along the firewall near the hood latch. I suggest that you may have knocked one or more of those loose in removing other things. Mine were originally all labeled, but those have fallen off. You say it doesnt crank, then I doubt that its a loose ground, since that would be a heavy cable down lower. The owners manual at the time was very informative if you have it, with locations and i.d.'s on a lot of the electrics. Good luck, keep us posted and dont forget to do an intro.

 

Hi jagxj40sydney,

Welcome to the Jaguar Forums! It's great to have you with us.

I can't recall for certain, but I'm wondering if that round white connector may be for the cruise control/speed control dump valve, which should be mounted on the wheel arch in that area. The dump valve holds vacuum when energized, but when the brake pedal is depressed or the cruise control switch deactivated, the valve opens, causing an immediate loss of vacuum to the cruise control actuator.

You can probably identify those connectors by their wire colors and location by reviewing the schematics in the manual available at the link below. Find the wiring color codes near the front of the manual so you will know that UG means a Blue wire with Green tracer stripe and BN means a Black wire with Brown tracer stripe.

Jaguar XJ40 Electrical Guide 1988-1989

Regarding your no-start, do the instrument cluster lights illuminate when you turn the key to position II (ignition ON), or are all the electronics completely dead?

Have you tested your battery? Jaguars need very strong, healthy batteries and a battery doesn't have to be very low on charge or capacity before the Jag becomes unhappy.

Cheers,

Don

 

The plug with the white face goes to the vacuum pump for the cruise control system, located under the ducting from the air cleaner housing to the MAFS.

 

The other connector attached to the dump valve for the cruise control, located under the vacuum pump