Ok, I have noticed my mileage starting to drop over time (from 27 on the highway to 20-21 MPG). It seems to be somewhat related to the outside temp as the warmer things get, the better my mileage becomes (19-20 MPG in the winter, 21-22 in the summer). So, I figured I would start with a simple flush of the coolant system to make sure all is good there. I will be replacing the thermostat as I think it is actually causing the motor to run a little cool, leading to a rich condition. In investigating the actual engine temp, I put the instrument cluster into the diagnostic mode (press and hold the "TRIP" button on the turn stalk, start the car, release the "TRIP" button once the instrument cluster shows "TEST"). I went through the whole gambit of stuff that the instrument cluster would show me. My question is this: most of the things had little to no notation of what the value was, is there a list somewhere of what each value is supposed to be related to? Some I could figure out like the engine RPM. I think I found the engine temp (noted as an "F" with a 3 digit number following it that was close to what I would expect the engine temp to be). But I am not sure if this is what I should be looking at. What makes me question it is the fact that it was bouncing all over the place as I was driving. I would anticipated a little bit of toggling between two temps that are side by side. This was bouncing over 10F in a 1 second period, but hovering around some common value over the long term. You let off the gas and the value would drop by 10-20, step on the gas and it would instantly rise by that much.

Any info that you can help me find would be greatly appreciated. If it is listed in the JTIS CD somewhere, just point me there. I have looked and all that I have found so far is simple references to accessing the diagnostic book. I've looked in the DTC section of the JTIS and it hasn't been of any help with this.

Thanks

 

Thermo,

You have an X-Type an that is the best mileage you are getting? My XJ8 gets 22-23 city and 28-30 highway!

 

George, yes, from day 1 that car has only ever gotten 27 mpg on a tank of gas. Occassionally it will sit for a bit at 28 mpg if I am cruising on the highway with the A/C off at about 70 MPH. Remember, the AWD sucks up part of the mileage due to the extra drag on the drivetrain. KNowing what I know now, I wish I would have spent the little bit extra on an XJ8 as that was really what I was wanting. But, I got in a rush because I found a Jag.

 

OK, for those that are curious where this is going, this is what I have found so far. I sat down and noted what all the different positions were and their values. I haven't figured out what they all mean, so, I will be updating this periodically. If you happen to know what some of these mean and I have a blank next to them, please let me know.

Of interest, these values were taken about an hour after I finished driving the car and only turned the ignition key to the RUN position and did not start the engine.

The first thing to come up is "TEST". Hitting the "TRIP" button again will get you into the below list:

GAGE - tests all gauges
(no words) - all segments are lit on the instrument cluster display
BULB - all lights are light on the instrument cluster
R 0406 - ROM Level
NR 0406 - ROM level plus type
EE 01 - EE Level for use when calling the manufacturer helpline
DT 1EC7 - DTC code as expressed in hexidecimal form
CF1 EE - 1st byte configuration setting
CF2 D0 - 2nd byte configuration setting
CF3 E2 - 3rd byte configuration setting
CF4 00 - 4th byte configuration setting
CF5 BF - NVM configuration (NVM - Non Violatile memory)
DTC E510 - cluster diagnostic code
E 0 - speed in MPH
0 - speed in KPH
SG 33
T 0 - tachometer (RPM) from engine
TG 30 - tachometer output to instrument cluster (value is 30-999)
F1 122 - main fuel pump pressure
F2 104 - transfer pump pressure (255-open circuit; >60 at idle; 28-29 the transfer pump is running, transferring fuel)
FP1 128 - fuel level #1 (driver's side?) range:0-255
FP2 102 - fuel level #2 (passenger's side?) range:0-255
FPT 90 - fuel system temperature
FG 428- fuel gauge reading, 0-999 range
451C - cylinder head temperature (451F?)
CG 92 - coolant gauge, 0-999 range, 92=68F, mid range on the temp gauge (200F) is 609
ODO 0 - range 0-255, counts up to 255 to count off 0.01 miles (roughly), then is sent to the ODO for addition.
UAP 0
CRC- 0
PTC 81
TRN 0
IVD 00
BATT 12.1 - Battery voltage, normally 12.0-14.9 VDC
OIL G - oil pressure switch (G-bad, 0-good, I don't get it, but that is what it says and I am guessing on the meaning of G)
BF-0
HB-G - hand brake (G-enGaged, 0-disengaged)
DB-B
SLP-0
IL 603
LC 363
ST 1000
DOOR-N - checks positions of all doors (N-all doors shut, F-one or more doors open)
STBT-F - Seat belt status (F-seat belt undone, N-seatbelt made up)
CR-0 - RUN/START sense circuit check (0-key in one of those positions, 1-key not in one of those positions)
AC-0 - RUN/ACC sense circuit check (0-key in one of those positions, 1-key not in one of those positions)
PAC 255
VIS-G
LF-0
RE-0
PATS 5C - PATS system status, 5C is key is good, ready to start/ vehicle is started
TFB-72
EVOLUME-C3 - automatic volume adjustment input value for the factory radio (?)
PA-42 - Port A value (hexidecimal value)
PB-20 - Port B value (hexidecimal value)
PE-0A - Port E value (hexidecimal value)
PP-00 - Port P value (hexidecimal value)
PT-E0 - Port T value (hexidecimal value)
AD1-75
AD2-64
AD4-220
AP0-D0
AP1-42

Hitting the "TRIP" button again takes you back to the top of the list to scroll through the list again.

 

Added a few things to the list. Been playing a lot with the car, seeing what all of these things stand for. HOpefully this will help others later on.

 

Hopefully, this applies only to the 'X'. More information than I need to know.

 

Testpoint, I'm sure this can be used for you car too. I am doing this to help those that want to really learn about their cars. It is interesting to see all the things that are available for you to use to diagnose your car that you end up paying others a lot of money to do for you. I am having fun playing with my car and seeing if I can figure all of these points out.

 

Sorry to spoil your fun but this might help you (please excuse the pagination):

ETM Test/No.
RH Message Centre Display
Gauge/lndicator/Display Tested
Range
Description

1 - SeIf-diagnostic entry TEST
.
Not Applicable
(N/A)
Establishes Self—Diagnostic mode.

2 - Gauge sweep GAUGES
Tachometer, speedo-
meter, temperature
and fuel rewind test.
Gauges display
current values after
test.
N/A
All gauges perform a
rewind to pointer stop.

3- RH Message Centre LCD.
Lower dot matrix
‘pixels’ activated
or all segments
activated,
RH message centre
LCD. LCD trip/
odometer display.
N/A
LCD function, prove out.
High series: Activates
lower ‘pixels’ of dot matrix
display. Low series: Activ
ates all segments of the
LCD display.

4 - Warning lamp LED’s BULB
All internally cont-
rolled lamps/LED’s
regardless of soft-
ware configuration.
N/A
Illuminates all the LED
warning indicators that are
controlled by the instrum
ent cluster. When this
test is exited current
vehicle warning lamps will
remain illuminated.

5 - ROM level ROM XX)(XIFAILInstrument clusterRead Only Memory(ROM).
N/A
Displays the instrument
cluster ROM level or ROM
checksum fault.

6- NVM level
NR XXXX
ROM level (most
significant bit) and
type (least significant
bit) as stored in NonV
olatile Memory
(NVM).
N/A
Displays hexadecimal
coding of ROM level or
checksum fault.

7 - EEPROM level
EE XX/FAIL
Electrically Erasable
Programmable Read
Only Memory
(EEPROM) level.
N/A
Displays hexadecimal
coding of EEPROM level
or checksum fault.

8 - Manufacturing date
DT XXXX
Final manufactunng
test date.
N/A
Displays hexadecimal
coding of final manufactur
ing test date.

9- Cluster configuration 1
CF 1 XX
Cluster configuration
settings (byte 1).
N/A
Displays hexadecimal
coding of cluster configurat
ion settings (byte 1).

10 - Cluster configuration 2
CF 2 XX
Cluster configuration
settings (byte 2).
N/A
Displays hexadecimal
coding of cluster configurat
ion settings (byte 2).

11 - Cluster configuration 3
CF 3 XXX
Cluster configuration
settings (byte 3).
N/A
Displays hexadecimal
coding of cluster configurat
ion settings (byte 3)

12 - Cluster configuration 4
CF 4 XX
Cluster language
configuration (byte 4).
00.
= Default language. 01
English UK. 02 French. 03
Finnish. 04 English US. 05
Italian. 06 Portuguese. 07
German. 08 Spanish. 09
Dutch. 10 Swedish. 11
Japanese. FF Not know.

13 - Cluster configuration 5
CF 5 XXXX
Cluster configuration
settings (byte 5).
N/A
Displays hexadecimal
coding of cluster configurat
ion settings (byte 5).

14 - Diagnostic Trouble Code
(DTC)
DTC XX)(X
DTCs.
Alternating
flashes of ‘DTC’
and actual DTC
value or DTC/
NONE).
Displays hexadecimal
coding of DTCs detected
in continuous operation
not during self test. If
DTCs are logged each
button press will cause the
next DTC to be displayed
until all unique DTCs have
been displayed. Display’s
DTC/NONE if no DTCs
present. Refer to WDS/
I DS to diagnose the instrum
ent cluster.

15- Vehicle speed (mile/h)
E XXXX
Speedometer.
---- to 4072.
Displays speed input
value after compensation
in tenths of mile/h, no
decimal point shown.
Speedometer will indicate
present speed. Displays ‘-
---‘ if message is not recei
ved or if received data is
invalid for two seconds or
more.

16 - Vehicle speed (km/h)
XXXX
Speedometer.
—-- to 6553.
Displays speed input
value after compensation
in tenths of km/h, no
decimal point shown.
Speedometer will indicate
present speed. Displays
-—‘if message is not recei
ved or if received data is
invalid for two seconds or
more.

17- Speedo- meter driver
SG XXXX
Speedometer.
.
Displays speedometer
driver gauge counts in
decimal.

18 - Engine speed
T XXXX
Tachometer. —-- to 6383.
Tachometer. .
Displays tachometer input
value in rpm. Tachometer
will indicate present rpm.
Displays ‘----‘ if message
is not received or if recei
ved data is invalid for two
seconds or more.

19- Tachometer driver
TG XXXX
Displays tachometer driver
gauge counts in decimal.

20 - Fuel system 1
Fl XXX
Fuel indication
system.
000 - 009. 10 -
254. 255. ---.
Displays present received
fuel level input 1 in
decimal, fuel gauge will
indicate present filtered
level. 000 - 009=Short
Circuit (below empty). 10
- 254=Normal range.
255=Open Circuit (over
full). ---=Missing.

21 - Fuel system 2
F2 XXX
Fuel indication
system.
000 - 009. 10 -
254. 255. ---.
Displays present received
fuel level input 2 in
decimal, fuel gauge will
indicate present filtered
level. 000 - 009=Short
Circuit (below empty). 10
- 254=Normal range.
255=Open Circuit (over
full). ---=Missing.

22 - Fuel system 3
FP1 XXX
Fuel indication
system.
000 — 254. 255.
Displays present filtered
Fuel level percent status
from sender 1 in decimal.
000 — 254= Normal range.
255=Open/Short detected.

23- Fuel system 4
FP2 XXX
Fuel indication
system.
000 — 254. 255.
NC.
Displays present filtered
Fuel level percent status
from sender 2 in decimal.
000 — 254= Normal range.
255=Open/Short detected.
NC=Not configured/option
not present.

24- Fuel gauge
I
FP XXX
Fuel gauge.
000 — 254. 255.
Displays present damped
total fuel level percent
status in decimal. 000 —
254=Normal range.
255=Open/Short detected.

25 - Fuel gauge
2
FG X)(XX
Fuel gauge.
N/A
Displays fuel gauge driver
counts in decimal.

26 - Engine coolant temperature
XXXX C
Temperature gauge.
-—-. 369. 5.
Displays last temperature
gauge input value from
CAN in 1/10 deg C, no
decimal point shown.
Temperature gauge will
indicate present filtered
temperature. Displays ‘---
-‘if message is not recei
ved or if received data is
invalid.

27- Temperature gauge driver
CG XX)(X
Temperature gauge.
N/A
Displays temperature
gauge driver counts in
decimal.

28- Odometer count
ODO XXX
Odometer.
—--. 0—254.
2550.
Displays the odometer
input value received via
CAN in decimal, value is
a rolling count.
=Message is not received
or if received data is
invalid. 0 — 254=Valid
odometer increment.
2550=lnvalid data.

29 - VAP
VAP XXX
Variable assisted
power steering status.
0—511. S-B. 5-
G. OL. FLt. EE.
NC.
S-B=Short to battery. 5-
G=Short to ground.
OL=Open load. FLt=No
comms fault. EE=NVM
checksum failure. NC=Not
configured/option not
present.

30 - Cruise control
CRC —X
Cruise control status.
-0. -1. -3. -7.
NC. --.
-0=Cruise off. - 1=Cruise
enabled, no function. -
3=Cruise resuming. -
7=Cruise on. NC=Not
configured/option not
present. --=CAN message
not received or invalid.

31 - Adaptive Cruise Control
ACr XX
Adaptive cruise
control status. Low
series only.
N/A
Not configured. Note: Test
in low series only.

32- Powertrain check
PTC XX
Powertrain check
status.
0- if.
Bit 0=MIL. Bits I -3=Red
throttle malfunction. Bits 4
-5=Amber throttle
malfunction. CAN
message not received or
invalid.

33 - Transmission check
TRN —X
Transmission check
status.
0. 1. --.
O=Transmission function
normal. 1=Transmission
fault. --=CAN message not
received or invalid.

34- Interactive vehicle dynamics
IVD XX
Interactive Vehicle
Dynamics status.
0— if. NC. —.
0= No faults. Bit 0= ABS/
TCS fault. Bit I Brake
intervention fault. Bit 3 =
Engine intervention fault.
Bit 4 = EBD fault. Bit 5 =
YAW/IVD fault. NC=Not
configured/Option not
present. --=CAN message
not received or invalid.

35- Battery voltage
BATT XX.X
Battery voltage.
N/A
Displays present battery
input voltage.

36 - Oil pressure
OIL -X
Oil pressure input
status.
-0. -G.
-O=Good oil pressure
(open). -G=Low oil press
ure (ground).

37 - Brake fluid
BF —X
Brake fluid level input
status.
-0. -G.
-O=Good fluid level
(open). -G=Low fluid level
(ground).

38 - Handbrake
HB —X
Handbrake input
status.
-0. -G.
-0= Brake off (open). -
G=Brake on (ground).

39- Dipped beam
DB —X
Dipped beam input
status.
-B. -0.
-B=Extenor lights OFF or
side lights ON. -O=Head
lights ON (dipped or main
beam).

40 - Side lights
SLP —X
Side light input status.
-B. -0.
-B=Side lights ON (B+). -
0=Side lights OFF (open).

41 - Cluster illu- IL XXX Cluster illumination 0 - 1000. Displays instrument panel
mination input, illumination duty cycle.
With vehicle lights on
value will change when
dimmer adjusted. Static
display of last value when
lights turned off. % Pulse
Width Modulated (PWM)
duty cycle in 0.1 steps.

42 - LCD lllumination
LC XXXX
LCD illumination
input,
0- 1000.
Displays LCD illumination
duty cycle. With vehicle
lights on value will change
when dimmer operated.
Static display of last value
when lights turned off. %
Pulse Width Modulated
(PWM) duty cycle in 0.1
steps.

43- Step dimming
STXXXX
Step dimming input.
0- 1000.
.

44 - Door ajar
DOOR —X
Door ajar Standard
Corporate Protocol
(SCP) input status.
-F. -N.
-F=Door ajar. -N=Doors
closed. Wagon liftgate not
linked to door ajar input.

45 - Seatbelt
STBT —X
Safety belt Standard
Corporate Protocol
(SCP) input status.
-F. -F.
-F=Safety belt warning
message OFF. -F=Safety
belt warning message ON.

46- Engine runl start
CR- X
Ignition status.
-B. -0.
-B=lnput is high (B+). -
O=lnput is low (open).
Should always be seen as
-0.

47 - Accessory circuit
AC —X
Accessory circuit
status.
-B. -0.
-B=lnput is high (B+). -
O=lriput is low (open).

48 - Auxiliary switch pack
PAC XXX
Auxiliary switch pack
status.
0-255. NC.
0-255=Displays auxiliary
switch pack status.
NC=Not configured (low
series).

49- Vehicle inertia switch
VIS —X
Vehicle inertia switch
input status.
-0. -G.
-O=Switch OK (open). -
G=Switch tripped
(ground).

50 - Washer level
LF —X
Washer fluid sense
circuit.
-0. -G.
-O=Coolant level OK
(open). -G=Coolant level
low (ground).

51 - Reverse switch
RE —X
Reverse switch sense
circuit.
-B. -0. NC.
-B=Reverse switch
engaged/on (B+). -
0= Reverse switch diseng
aged/off (open). NC=Not
configured.

52 - PATS
PATS XX
Passive Anti-Theft
System (PATS)
status.
O-FF.
Displays hexadecimal
coding of PATS status
byte. O=No Diag Byte.
1=Bad Diag Byte. 2=Start
Byte Received. 3= Key
Read Complete. 4=Key Is
Programmed. 5Bad
Read Address. 6=Signa-
ture Matches.

53- TFB
TFB —XX
?
O-FF.
High series only.

54- EVOL EVOLUME —XX
?
O-FF.
High series only.

55 to 59- Not required
PA -XX to PT
—XX
.
N/A
Not required.

60 to 63- Not required
ADO -XXX to AD4
-)(xX
.
N/A
Not required.

64 to 65- Not required
APO —XX to APi
-XX
.
N/A
Not required.

66- Back to test
2
GAGE
Tachometer, speedo-
meter, temperature
and fuel.
N/A
Repeats display cycle
from test2.

 

U, no problem at all. I was kinda hoping for something like that. Lets see now if I can figure out why my mileage has dropped.

 

Could it be that your foot has gained a little weight!!??

 

George, no, if anything, I am driving a bit more light footed now. I can drive the same things I did back then and get a few less MPG. Oh well, on the perpetual search for more MPG (atleast getting what I had back).

 

The two biggest measurements for fuel supply calculation to a fuel injected engine are: -
- Mass air flow
- engine temperature

the other measurements are just trimmers, (like air temperature), although throttle position and its rate of change can impact things when the driver wants to accelerate quickly, but this is outside the cruise situation described here.

So I would suggest investigating the two things above first.

 

Fraser, the reason why I got on this track was because of engine temps. It wasn't so much that my car was running hot, but I knew it had been atleast 2 years/30K miles since the coolant had been touched and I figured it would be a good time to look at things. Well, I thought I knew how the thermostat was mounted in the car and found out I was wrong. Needless to say, I messed up the thermostat to the point that the car after a few minutes at highway speeds would be just off of the C mark. yep, running a bit cool there. Surprisingly, that didn't affect the mileage all that much. Even at that cold, the motor was still pulling 20.6 MPG. I have since replaced the thermostat from my abuse and I also put on a new coolant sensor to start eliminating things. Granted, watching the instrument cluster (test mode), the computer is seeing the motor at 90.6C (about 195F). So, that is fairly normal for the car. We'll see where things sit now that the new thermostat is in there.

I may end up trying to clean the MAF again, but that didn't seem to affect anything the last time I played with it. I am thinking with 110K miles on the car, it may be time to start looking at the O2 sensors. BUt, that will come with time.

 

Thermo, don't know if you have similar issues where you are, but here in California, they change the gasoline formulation between winter and summer - in winter adding 'oxygenators' (read ethanol or equivlalet) as some kind of emission inhibiter for the cooler weather.

Since they started doing this, every fall/winter, I see about a 5-10% reduction in gas mileage, returning to normal in spring/summer when they get rid of the additive.

 

Quad, yes, I notice a 1-2 MPG drop in my mileage in the winter due to the gas mix. But, I am comparing summer mileage to summer mileage. I am trying to remove as many variables as possible.

 

Thermo, with 110K miles, I think it is time for a new Jaguar!!

 

George, don't be tempting me. That XF is looking mighty tempting. But then, I am really wanting a Ford Superduty, but that is a different discussion all together. Time will tell. I like what I have currently (03 Jag-DD and my toy, a lifted 97 Expedition). The combo of the two do what I need at the moment. But, if I get the house I want, I will need something that I can put about 3 ton in the bed of and not worry.

 

Thermo,

Your doing a great job with this "dioagnostic mode" analysis. Just when I thought I was getting educated on my car, along comes your thread about an important tool I didn't even know existed and it's right in front of me nose. Is there any info in the JTIS on this topic? Do you think your analysis applies to my 05 XJR as well?

 

tarheal, this same diagnostic tool should work on your car too. Worst case, go out and try it. Press and hold the "TRIP" button, rotate the key to the "RUN" position and wait for the instrument cluster to do something. It will be obvious after a few seconds if the car went into this mode or not. The only thing I would do is look at the instrument cluster as you are going through the list and see if the letters match up. I think you will find that it will be pretty close.

As for what the JTIS says about this, it is silent about this. It may be hidden some where else and I just haven't found it, but most of the things it talks about when it comes to diagnostics involves the special dealership only computer (well, not dealership only, but more money than most of us are willing to spend for in our garage). I am doing some more looking, but I am not holding out any hope at this point.

 

A copy of the TSB that discusses this diagnostic tool is here:

http://jaguar.bttlxe.com/xtype/Addit...%20Cluster.pdf