I'm in the process of cleaning up some loose ends now that the highways are bare and I can get out and drive.

I have an adjustable interface between the GM PCM outputs and the Jaguar speedo/tach inputs so that I can match the Jaguar instruments to the Chevy RPM/MPH outputs. The tach works fine and the speedo works, just needs adjusting, but the odometer and trip meter DO NOT work at all. When I look at S57 I see 12v(G) into the speedo, ground(B) out of speedo, and the signal wire(Y) coming from the Jag pulse generator, trip computer, service interval counter, and cruise control. The Y wire from the sig gen has to be the source for all the information used by the other devices, including the speedo. So my interface speed output is connected to the Y of the speedo and, as I said, it works. I am not using the cruise control, trip computer, pulse generator, and the OXY warning light is being used for the "check engine light" (CEL) of the Chevy PCM. But none of that should matter, in my mind. Would anyone have a guess why the same PPM coming from my interface to operate the speedo correctly won't operate the odometer? Same wire, same frequency signal, just different source.

The easy answer might be that the odometer just doesn't work, but I tend to believe that it was working when the car was parked-19 years ago. Any help is appreciated.

Dave

 

I think it's the odometer itself or some other fault within the speedo itself. More of a hunch than anything else.

Let's hear what others have to say


Cheers
DD

 

Like Doug says, could just be the odometer, as mines hooked up same way and odometer works fine,

 

I've got a spare speedo head if you want to borrow it. never mind, send address, You can have it.

Larry Louton

 

[Larry Louton] I've got a spare speedo head if you want to borrow it. never mind, send address, You can have it.]

[Darrenmb] Like Doug says, could just be the odometer, as mines hooked up same way and odometer works fine]

Thanks for weighing in all of you, I think I will have to face the probable truth. Thank you very much for the offer Larry, I'll keep this one and maybe have a look inside some day.
Darren, I probably should have PM'd you first, that would have answered my question. Thanks

Dave

P.S. Let's just consider this the end and resolution to this thread. Any more posts are of course welcome.

 

Well, I worked up the bravery and decided to work on the speedo/odometer myself, emailed two instrument repair sites and both said "......Jaguar? No can do".

Was not too bad, bending back the bezel tabs was probably the hard part, but with patience and small pointy tools, it will come off. Pry the speedo pointer straight up/off and remove two very small screws holding the number plate on. I jiggled the wheels and gears and finally found that the 1's and 10's wheels of the odometer were bound up with each other. Taking that shaft and the wheels apart seemed like something I would regret. I fiddled with it a little and voila', they came loose from each other and everything worked as it should when I turned the trip odometer servo by hand.

Put everything back together and will return it to the dash tomorrow. Still leaves the HVAC inactive, but as they say, "baby steps"

Dave

 

How are you doing the ac? I originally set mine up to work on jag wiring etc, but that leaves no safety systems, so I currently have the power wire to compressor pulled off, and new tune ( for when i do heads and intake) was built from an impala tune, as it doesn’t utilize an evaporator temp probe that my donor used, so I will simply be finding the wire inside that turns compressor on and soldering it to the ac request signal on lt1 pcm, then just plug the lt1 ac power back onto compressor as I have already wired the rest! 🤞 fingers crossed it works! lol

 

Oh and great job on figuring out your odometer on your own! Saved yourself a few Pennies there

 

Darren,

I haven't tried to connect the A/C yet, not that important up here yet. The issue is nothing works on the unit. I bench tested everything before I reinstalled and it all worked, I am using the Jag Aire manual controller for the servo because I didn't know if the original amplifier would work. Everything worked on the bench. I have checked the fuses, but I get NOTHING now. Temp/Function knobs do nothing; manual servo switch does nothing (no whir, click, hum, etc.); no flap movement; "road air" comes out of all vents at the same time, that doesn't seem right; ...no nuthin'. My first suspicion is simply a lack of 12v somewhere, I just need to spend some quality time on it.

I lucked out on the speedo, I dreaded going into it, but knew I had to.

Dave

 

Do you have 12 volts at center big brown wire at Blower relay?

Larry Louton

 

I've been going over the schematic, Larry, and it looks like that is a spot to test for 12v constant. I'm thinking the G wire to the Mode Switch should be tested for 12v switched. Does that sound reasonable to you? I'll have to wait just a little longer until the shoulder lets me crawl around on the floor boards-almost there. The really sad thing is the weather is not bad enough that I need a heater and certainly not A/C, so I'm a little low on incentive.

Dave

 

.

 

Hello LT1, You will indeed get a parking spot in Jaguar Heaven. It is easier if you check for output at the Brown (N) at either the Amplifier or the water temp thermistor switch. When you look at that big brown wire at Blower relay it is actually Brown and white tracer, (NW). If it looks like your going to be spending a lot of time on the left side of vehicle, Take the steering wheel off, It prevents you from hitting the back of your head with it.

The weather sounds real nice up there.

Larry Louton

 

Larry, Thanks for the tips, especially about the steering wheel. Sounds like you've been there.

Dave