I'm debugging turn signals on one of my '93 4.0L convertibles. No signals, no hazards, no flashing of any kind. I've been using the '93 Electrical Guide to great effect; I have learned a ton about my car by slowly absorbing these diagrams.

• Hazard switch and flasher relay have been A/B tested in my other car and both work. Initial check on the #5 7.5A right(passenger)-side fuse is good.
  
• Bulb sockets and wiring have been addressed to provide resistance for the flasher.
  
• Starting with the multi-meter at the flasher, the ground is good (great, even) but no voltage when the key is on (position 2 and engine running).
  
• Moving upstream to the hazard switch, again good ground/no voltage (I'm intentionally ignoring the battery-powered side of this switch and only pursuing ignition voltage for the moment).
  
• The fuse panel is next; skipping that I find myself at the auxiliary load/ignition protection relay. Good ground, good voltage! Removing the relay causes a bunch of stuff to stop working (windows, horn, etc.), reinstalling it restores functionality (except the lights, of course, heh).
  
• Gotta be the fuse after all, right? Replaced the fuse but no go. No voltage on that fuse slot.

Wth? According to the diagram, these fuses (slots #2, 5, 7, 8, 15, 19) use a single large block connector, the relay has its connector, and between them appears to be a single post or junction for splitting the (white/pink) hot line from the relay to the various ignition-switched accessories (such as the aforementioned windows, frex).

Anyone seen something like this? What am I looking for? Somewhere between the relay and fuses I dropped 12V. Suggestions welcome!

 

I read the diagram a bit differently in that the horn is not fed via load relay (it is battery fed), the cigar lighter is as are the entertainment unit, climate control and A/C compressor and seat heaters. The windows are but appear to be fed via a separate spade on the load relay and then by white/blue wire. Are you sure all those components other than the flashers are actually powered on. If only the windows are powering on the problem may be an internal break in the load relay at one of the 87 spades. You said you had another car, can you substitute another load relay to check? If all those other components are working OK it may be at the LBS47 splice in the white/pink wires.
(All this is Just a slightly educated guess)

 

Thanks for the reply!

My other car recently failed a smog test and it's in the shop getting a bit of a tune-up. I'm hoping to get it back today. A swap test will definitely tell us whether the relay is the culprit for certain.

After reviewing some of the other ignition-switched branches, I agree that many of them involve other power sources than the aux load relay. However, the cigar lighter appears to be a very simple circuit directly off the same 87 relay terminal, and ought to provide a valid test point for the relay in regards to the turn signal power circuit.

So my next action is to swap the relays if my other car is available, or test the cigar lighter if not.

 

Okay...

So I wrote a follow-up post Wednesday night, submitted it (I thought) and then ran out get some other stuff done. I must of hit the wrong button; the post may have been eaten by a grue.

I did finally get this issue sorted out. I pulled the passenger-side fuse panel (the whole ground plate it's mounted to) to access the back side. I learned a lot by doing this, particularly the fact that I've been misunderstanding how the fuses are mapped on the panel!

If you turn the table on the access panel counter-clockwise to read the position numbers from left to right, the first fuse slot is in the bottom row. This is wrong. Duh! All this time I've been checking the wrong fuses. As far as I can tell, there are no markings or instructions from Jaguar explaining precisely how the fuses on the panel are located. The actual fuses currently in the panel provided no clue, either, which I'll explain, below.

For the record, fuse #1 is in the top left slot, natch.

Anyway, in the warm light of a sunny Saturday morning with access to all the points I needed to look at, I was able to perform a lot of good testing. The aux relay has good ground and good voltage on both inputs. I found continuity along the white/pink wire from the relay to the fuse panel, and I was also able to find good voltage from the fuse panel at the correct position. This all looked good.

That led me back to the hazard switch. I'd previous cleared the switch by swapping it between my other car a few months ago. However, I am now finding continuity and voltage at the green input wire from the fuse panel, and failing to get voltage at the light green/pink output wire. So out the hazard switch comes, at the pigtail connector.

After examining it a bit, I decided I wasn't happy with the switching action compared to the rear defroster switch next to it. I'd previously exercised the crap out of the switch, just as Doug often recommends. Today I tried unsuccessfully to pry the switch out of its housing, but I was able to create enough of a seam to soak some WD-40 into the switch and exercised it vigorously again. This improved the feel and sound of the 'up' state dramatically (the down state clicking was already pretty decent). I then put it on the bench and tested continuity between the relevant terminals for both states successfully.

Reinstalling the switch and putting all connections back to normal fixed the turn signal circuit. I'm not sure what happened when I A/B tested the switch back at the beginning of the Summer; I've slept too many times since then and I just have to chalk that up to experience at this point.

So problem solved, but I have a fun follow-up for y'all that fits the topic of this thread perfectly. When I first started looking at the electrics on this car, this is what I found in the passenger-side fuse panel (I took pics I've been saving for this topic):





Now I have to note that the electrical gear in this car works great for the most part. This XJS gives a very good user experience on the surface, and a lot of accessories that are notorious for failures all work fine (heated seats, frex). So despite the massive WTF moment I got from seeing this (which isn't helped much by my better understanding the fuse layout), I haven't gone through and simply pulled all the fuses and started over from scratch yet. Once I've sorted all the bugs out of the car on a case-by-case basis, I plan on refreshing both under-dash panels with all new correct fuses (the driver's side panel isn't quite this badly provisioned, but it's close).

 

One more on-topic followup. There is a missing part to the right of the passenger-side fuse box. You can see the broken mounting tab in the picture below. There is also a medium-sized connector hanging lose with a distinctively un-automotive look to it that seems like it might of plugged into something that isn't there anymore, seeing as everything else nearby is fully connected already.


Missing part (not) on the panel with the ignition power relays, just below them.


Vestigial loose connector? Apologies for the auto-focus-challenged photography.

Anyone have any idea what is supposed to be here? I'll go digging into the other car eventually, but I thought I'd post this question for fun.