My left rear window is driving me nuts. Most of the time it will not work. Today, outdoors, I took the door card off and disconnected the window motor from the wiring coming from the switch. With the engine off, a meter on the wires from the switch shows 11V and switches polarity as it should when the switch is toggled in each direction. So I concluded it’s not the switch. Then I applied 12v from a battery charger to the motor wires. By switching the +ve and -ve, the window goes up and down as it should. So I concluded it’s not the motor. The wiring from switch to motor on the S2 is connected by bullet connectors. I cleaned them and reinstalled them - no improvement. I cut them off and replaced them with insulated spade connectors on each wire. No improvement. I left the door card off and put the car back in the garage and, you guessed it, when I tried the window it worked. Later I took the car out for a drive and the window would not budge again.
Any ideas? I might try removing the wiring connector and temporarily twisting the connections together and insulating them - just in case I made a bad connection when I installed the spade terminals. If that doesn’t get the window operating consistently, what’s left? Replace the motor in the hope that fixes it? The motor looks a tricky thing to get out so I’d like to be sure I have tried everything else possible first. Any suggestions, please?
David,
Have you tried swapping switches with another window to see if the problem follows that switch? 11V seems a bit low at those connectors. Maybe just a little too low for a 40+ year old motor to get moving (although I have never measured that on any of my Jaguars)?
Thanks for the prompt response. A good thought, Paul, but the window has two powered switches - one on the console and one on the small console in the rear. I tried both and they both provide the same 11v. Also, on my S2 the switches do not have a single plug to connect all the window wires to the back of the switch - oh no, we are dealing with earlier thinking here and each wire has its own spade connector on the end of the wire. This makes removing and reinstalling switches a bit daunting. So, how about I just take the door card off a door with a working window and test the voltage I am getting from the switch to that one. Would that comparison be valid for eliminating the switch?
a bit like “Groundhog Day”, it seems … didn’t we have a similar thread just some months ago? On SII cars the window switches are interconnected - there even was a nice diagram recently.
The rear left window is probably the last in line, so it will kind of collect any and all (intermittent) circuit faults of the other three windows. It seems your problem might be located in an intermittent interruption of power supply upstream. Power Window Switches SA178.pdf (423.3 KB)
Jochen, thanks. Yes, the left rear window IS the last in line. If it had been intermittently flickering or showing no voltage then it would look like an problem in the supply reaching the relevant switches but since testing the power from the switch with the meter always produces a steady 11V then, surely, that rules out an upstream problem? Please correct me if I am wrong.
No, of course, you’re right - I should have read your original post better. If you’re with correct switching polarity and power at the door, the switches are out of the game. As a consequence of the wiring pattern and the many connections leading to the last switch 11 V might be quite typical.
What happens, if you put the wires for the rear left window to the right hand front switch? Both in terms of voltage (does it rise to more about 12+ V?) and effect on the window? Maybe there is some sort of “brake loose” effect in the electric motor (I once had a slot car controller where resistance changed very rapidly:-) making it operate only at higher voltage and leading to operation when/if for any reason resistance is reduced or voltage rises.
On a Series 1 there is an intervening circuit breaker in the power windo circuits. It’s located down on the left hand side of the footwell behind the panel. It’s purpose is to protect wiring from multiple switch operations (different windows). Did this design persist into the Series 2? I have had mine play up. Paul
David,
Yes, I believe that a comparison of the voltage at the right rear window motor would be worthwhile. That is easy for me to say since you are doing all the work.
It sounds like the SII is similar to the SIII cars in that the power for the rear windows goes through both the front and rear switches on the way to the motor. I have encountered numerous similar window issues in my SIII cars and fixed them by removing the switches, disassembling them, cleaning the electrical contacts with a pencil eraser and spray electronics cleaner, reassembling, and reinstalling my SIII window switches. Some tarnish on the electrical contacts in either or both switches would increase resistance and result in lowered voltage available to the motor.
If I were you I would first test the voltage at the right rear motor that works and compare that to your left rear motor, then I would remove the front switch for the left rear window, disassemble it, clean the contacts, reassemble the switch, reinstall the switch, test again for the voltage, and test again with the window motor connected. Then I would remove the rear switch for the left rear window motor, disassemble it, clean, reassemble it, test yet again for the voltage, and test again with the motor connected.
I highly suspect that like the SIII cars that cleaning the contacts inside the SII swtches will reduce resistance in the circuit, increase voltage available to the motor, and get the window motor working properly again. And why that worked will be evident in your test results.
I would also clean the two switches - also coming from the s3 - and 11V sounds about right. What happens under load?
With jumper cables directly to the battery my window is noticeably quicker.
I had an intermittent failure recently but it resolved itself. Everything is clean and has been gone over…
**
It’s a peculiarity of electrics that you may have 12V without any current flow, David…
Which makes plain voltage checks with a meter unreliable - a test-lamp, drawing current, is a better test. However, a motor draws very high current initially - so a substantial test lamp is advised. And may be this motor’s lift mechanism offers more mechanical resistance than the others…?
A bad contact upstream may restrict current flow. I assume the other three windows works correctly - in which case I suggest you clean contacts of the next switch up-stream?
I bet it’s the switches.
You should try measuring things with everything connected and see what voltages you get when the window is not working. As Frank said, having voltage doesn’t necessary means that the switch’s dirty contacts don’t have very high resistance, and thus a huge voltage drop under load.
Also, bypass the circuit breaker for troubleshooting.
If the SII system is the same as the SIII, current has to travel from back to front to back and front again, many meters of flimsy cable and two switches in between…
Adding relays transforms the windows operation. My rear windows would almost stall… now they all go up and down with a jest.
The S3 is positive on both leads and grounds one side respectively. This means power has to go all the way to and from the window.
I put in relays per your description and installed them (front windows only) below the armrest compartment, mainly to save the switches. If I ever did this again I‘d put them into the A pillar. They can work very well per factory, though - my passenger window was always very quick, even before!
I meant load testing - maybe a headlight bulb or just the voltage at the connectors (while winding the window up) - broken wiring or a dirty switch can still show voltage but does nothing under load.
Thanks, everyone. I will do some testing/playing around and get back with any findings or progress. Any swapping switches is a bit daunting on the S2 as I said earlier as the wires each have their own spade connector as opposed to the nice plug fitted on most S3s ! The S2 switch is part is DAC1301 vs the DAC2747 on most S3s.
Aye, I think most Jaguar guys have learned the widow switch cleaning protocol at some stage of the strewardship.
Aye, again, easy thing first.
Hope this thought turns out unnecessary . That window motor is on the way out. Intermittant response to either 11 or 12 v. An olden DC motor “trick”. Catch i it in failure mode. Whack t a bit. Try the 11 v. It may come alive.
Caveat. Not a fix, merely a test for a failing motor. And, it may not respond. Thusly, the question remains .
An other, “fix”. Fuzzy a bit here in execution. Supply a healthy 12 v via one or two relays…
Some other chores are taking most of my time today but I did test voltage coming from the switch to the righthand rear window. 11v from the switch. The same as the left but the righthand rear window operates every time whereas the left hand did operate once today then stopped working again.
I also found a spare switch and cleaned and tested it. I’ll use that when I start swapping out switches as per Paul’s suggestion above.
From previous posts by Aristides and David, I have the SK Jagtech schematics for adding relays. I will be trying to get my head around how they work this evening.
David,
When I disassembled some of the window switches from my Series III XJ6 parts cars I discovered that some of the internal electrical contacts were very bad tarnished and discolored from heat. I was amazed that some of them worked at all.
I know that the Series II switches are larger but they might have the same issues and resolution.
Yes indeed, Paul, the one I cleaned today (a spare) was blackened on each contact. I sanded them and wiped them with rubbing alcohol as best I could (two contacts are lying flat in the bottom of the switch cavity so hard to sand) Inside S2 switch but the tests showed no resistance across the contacts after cleaning.
Another challenge I have discivered re. the schematic I have found for adding relays (if I end up needing to do that): it looks like the switch poles are not numbered the same way on the S2 v later S3 switch but I am still trying to work all that out.
David,
I have had good luck cleaning the hard to reach electrical contacts inside the SIII window switches using the eraser on the end of pencils. It is abrasive enough to do the job and small enough to reach the contacts. I use both a back and forth movement as well as rotation of the eraser while rolling it between my fingers until the contacts are clean and shiny.
This should also work inside the larger SII window switches.
Paul
