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Good Day, My symptom is that the cruise control function will not activate.
A short history of this car is that it was delivered new to Canada (Toronto)
The first owner had it for 11 years and took good care until involved in a low speed front end collision. The insurer refused fixing it and sent it to auction.
The second owner also owned it for 11 years. He ran it through his business which is one where damaged cars are renewed.
He replaced both air bags and sensors, both headlamp assemblies, new alternator and air conditioning compressor, repaired the hood and had the car painted
Current mileage is 42000 ( 73000 Kilometers)
.1 It is not the switch at the brake pedal - meters properly
2. It is not the switch on the console - meters properly to ground
3. I removed the vacuum switch solenoid assembly and did some tests.
- two of the solenoid assemblies will change position if twelve volts is applied
- the third solenoid makes no noise when voltage is applied, At rest it allows vacuum to be read at its exit point
- the vacuum tanks are not leaking - you can hear air returning into them if the hose is pulled (engine running)
4. I bypassed the entire vacuum assembly just discussed and applied full vacuum to the assembly attached to the throttle body - no change in engine rpm - no apparent leak
5 vacuum measured out to be 18 inches of mercury
6. One time, I left the cruise switch in active mode while driving. As I slowed for a red light, the transmission shut down (I think into limp home mode). I did a power off/on with the ignition switch and the problem cleared
7. Since I purchased the car, I get a secondary check engine message after system diagnostics run -
8. My rather ineffective OBDII reader claims the system test always fails at P0000
9 Should getting a better reader be the first step?
I will much appreciate any suggestions with regard to this knotty issue
Hi,
I can't give you any first-hand knowledge as my car doesn't have cruise, but you may have an underlying ABS issue here. The basic OBDII readers won't pick up those codes, and I've read of at least one instance where a reader triggered spurious check engine messages.
Your quickest route might be to have the codes read by the Jaguar-specific kit - some indies will have this - and post them back here (actual codes, not any interpretation of them).
Could the P0000 be P1000? If so, it simply means that the OBDII monitor testing is not complete and not a fault per se.
Sad but true that the low residual value of our cars can destine them for insurance writeoff with only relatively minor damage
If you have an android phone, the Torque Pro app is pretty cheap, and works with a very cheap OBDII ELM 327 device ( amazon, ebay) to read most of your codes. A good place to start. My cruise was also screwing up, but was fixed by repairing the ABS module.
Have you checked the wiring to the ECU? I have a similar problem although mine does not throw the gearbox out. Are you sure the gearbox issue is related? My cruise would very very infrequently decide to suddenly activate and be able to be used.. then after a few minutes.. time could vary.. it would then not work again.. The only option I have left with mine is to check the wiring back to the ECU as I am inclined to think mine is a wiring fault. I too have checked solenoids and they work plus vacuum.. I posted a message on here some time ago.. I dont think there is much knowledge on the older cars cruise..
The first was a poor ground due to a pinched wire in the steering wheel. The black wire from the buttons connects to the black wire for the sound system volume buttons. It makes a very tight turn there which resulted in a break.
The second problem was withe the copper wipers inside the throttle body not making a good contact with the tracks in the left side cover. Bending the wipers a little more fixed that problem.
There is a circuit trouble shooting procedure in JTIS21 that is very useful and you should give that a try.
Nice comment.. I am soon to try and dismantle my throttle body to get it bored somewhere.. that is where i will investigate this.
Timely as I was looking at the info on jagrepair.com... an interesting comment relating to the temperature.. as my problem was intermittant and i feel temperature dependant in a way.. and the tracks can be affected by temperature when they are worn... Thank you
This seems more complicated than cruise control activation, with various symptoms that do not seem to be cruise control related (transmission limp home, for example).
But to be specific to start, you have a cruise control switch that lights up when you push it. You get to highway speeds (cruise control will not activate below about 16 mph based on wheel speed), you try to set cruise control, and it does nothing? And you have no ABS or ECM codes?
As noted above, it might be hard and time-consuming to diagnose such a problem with many possible sources without either a good ODBII reader or some CAN scanner. I wouldn't necessarily, however, start at, say, the throttle body
I wouldn't start with the throttle body either, unless cc quits after 15 - 30 minutes. The best place to start is with the JTIS trouble shooting procedure.
Well, I took the ECM suggestion and started there. I disconnected the battery and the connections to the ecm. There are two wires from it to the switches. One from EM10 pin 11 to the input side of the brake cancel switch; the other from EC11 pin 4 to the input side of the cruise control switch on the console. Both use the same power point on driver side fuse box, fuse 11. I misinterpreted the end point and measured to ground, getting 425 and 440 ohms for the two points. Further investigation showed I should have removed fuse 11 and tested at that point. The fact that I got a measurement at all suggests that the two wires are not broken. Reassembly went well with no new issues.
I should clarify the symptoms
1. The red led on the cruise control switch never turns on
2.The transmission issue is probably unrelated to the cruise issue - happened just once
3. I always get a message "engine fault" with the amber warning light
4. my obd reader will not give P1111, Always P0000
5. I started the engine and began testing the vacuum driven piece that is used to operate the throttle body during cruise control action - still no apparent ability to move the throttle
6 This action generated a new fault code P1226 wich reads "mechanical guard sensor range/ performance" - this is a safety assembly designed to prevent the cruise control from causing acceleration if the electronics fail, probably prevents the vacuum device from operating.
7. a secondary comment in the description states "When Amber MIL is activated (DTC Logged; first trip), ECM inhibits cruise control"
8.I also got a "Vehicle Poor Performance" message.
9. Fortunately, I was able to clear this code
10. I have to conclude that I'll never get the cruise control to work until I clear this generic "system fault" message.
11 I will research the suggested OBD reader - but am leaning toward the Jaguar I930, based on its description - Any Comments?
1. Even if the wires are not broken, you might check directly to see if the console switch is working with the LED burnt out. E.g. turn the switch on, then measure resistance ECM (EC11-4) to driver side fusebox #14 (FC5-8), remove fuse as you note, or for grins, try in both switch positions. If one of them is a couple of ohms or less, the switch works. But, I suspect you should go to 3 and 10 below first (or the JTIS procedure...). Edit: I eventually saw you did something like this above.
3. You may want to diagnose this first.
4. As above, are you sure this is not P1000?
10. This may be correct, depending on what the problem(s) is (are).
11. Comments from me. I have several things, none are perfect. One is a foxwell reader (NT-510) with the JLR software, has its limits, but has found all codes to date. The other is the the SDD/IDS from British Diagnostics, much more useful in theory. Running it under Win10 with a WinXP virtual machine has been not particularly bullet proof for me, but I have had no problem diagnosing or resetting individual codes with this. My issues have come with module reprogramming.
Like the throttle body, I might not start with the vacuum system in the initial steps to diagnosing any of these problems.
Relevant part of the 97 xk8 electrical diagram below:
Poster, did you say you can't change speed with vaccum on the throttle port? Well that's how 1997 and 1998 cc changes speed. When I read this I thought about the time I lost cc, light went out, got restricted performance message.
Turns out the vaccum hose came off the throttle. Seems to me that you might have a vaccum leak at the throttle if I read your previous post right. Applying vaccum to the port on the throttle will increase rpm/speed in a proper set up.
If I mis read your note, maybe my experience can help you somehow.
Interesting.. on my side i have never applied vacuum whilst running to see if the engine revs rise.. will it occur whilst just idling and then try and apply vacuum?
I do not have fault codes of any kind no vacuum leaks and have tried a number of switches.. always aim for the simple. have also replaced the brake switch. ECU has been tested too
Using sdd my steering switches were tested, brake switch tested, cruise switch tested. That diagram does not show the wiring to the vacuum mechanism does anyone have that?
An interesting point on one of the above posts.. when my cruise light did come on.. and i then thought, ah great try the cruise.. it was fine until it was on a load then the light would go out and then i wouldn't see the lighted switch again for some time.. Actually not seen it for a bout a year.. like a long lost friend...
That would be great if you could test this vacuum point.. Jpattr7 and says his does not change when he applies vacuum there so wondering whether this could be his issue. Hope not for him and for me if I have to test as presumably that means a new throttle body.
Im think a quick and simple way to do this.. if you haven't got any vacuum pull equipment handy is.. if you have an xkr, pull off the vacuum hose on the supercharger.. pop it onto the throttle body and see if revs increase while engine running.. quick and simple and i clear any codes that might be generated once popped back together.
Logic be dammed. I just started her up, connected a vaccum pump, plugged the original vacuum hose, and created a good vacuum to the reservoir above the throttle.
NOTHING happened! I disconnected the vaccum pump and could hear the release of pressure cause the valve, or whatever the resivour is connected to, go clunk. Repeat process 2x = same result.
Experts? Any ideas? Believe me this vacuum moves (manages?) the throttle to cruise control. Throttle will not increase, cc is disabled, and restricted performance amber light displays without this vacuum as soon as cc tries to increase speed.
RJ237... you say theres a wiring fault finding JTIS.. is that for the throttle body? or the wiring? Wondering whether we can find if the tracks in the throttle are bad using the volt meter.. Would have been nice to have the simple solution found. After this it is then only the continuity of wiring from the ecu to the solenoids.. I know they work as a while ago i gave them 12 volts and there was movement.. Jpattr7 How are your investigations going?
Kent, I've got a copy of the service manual open on my computer. Extensive details on troubleshoot cc failure. Too big to post here. Message me if the above offers are not redundant with my findings.
10-09-2019, 04:38 PM
1997 convertible cruise control not activating
