intresting TPS info
03-23-2009, 11:28 AM
#1
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Year: 1991
Model: Cherokee
Engine: 4.0
intresting TPS info
Automatic Transmission Service Group
TPS CODE P0123 WILL NOT CLEAR
COMPLAINT:
CAUSE:
CORRECTION:
A late model Jeep with a 2.5 or 4.0 liter engine and the AW4 transmission comes in with the
“MIL” Lamp illuminated and a complaint of late shifts. A scan reveals a code P0123, “TPS
Voltage High”, is stored. The scan tools data list indicates that the TPS signal wire voltage is
at 5.0 volts at closed throttle, and then ranges up to 11.5 volts. A backup check of the TPS
signal wire (usually is an Orange/Dk Blue wire), shows 5.7 volts at closed throttle, with a
similar rise in voltage as the throttle is opened. A check of the TPS 5 volt supply and ground
circuit prove that both of these circuits are good.
A check of the TPS signal wire with the TPS disconnected shows the same 5.7 volts. The
technician now begins an inspection of the wiring between the TPS and the PCM and TCM to
no avail.
A replacement TPS does not cure the problem, neither does replacement of the PCM or
TCM.
The Switch Sense circuit in the Clockspring in the steering wheel hub has shorted to battery
voltage from the horn button circuit. When the Switch Sense Circuit shorts to the 12 volt
HORN circuit the TPS signal voltage is driven high and remains there as shown in Figure 1.
This is because the 5 volt reference voltage used by the Cruise “Switch Sense” circuit and
the TPS are shared inside the PCM.
Replace the Clockspring assembly. Once the Clockspring has been replaced, be sure to
check the sensor 5volt reference voltage at the PCM to insure that circuit has not been
damaged by the short to power. Also check the TPS signal range to insure the TPS has not
been fried.
TPS CODE P0123 WILL NOT CLEAR
COMPLAINT:
CAUSE:
CORRECTION:
A late model Jeep with a 2.5 or 4.0 liter engine and the AW4 transmission comes in with the
“MIL” Lamp illuminated and a complaint of late shifts. A scan reveals a code P0123, “TPS
Voltage High”, is stored. The scan tools data list indicates that the TPS signal wire voltage is
at 5.0 volts at closed throttle, and then ranges up to 11.5 volts. A backup check of the TPS
signal wire (usually is an Orange/Dk Blue wire), shows 5.7 volts at closed throttle, with a
similar rise in voltage as the throttle is opened. A check of the TPS 5 volt supply and ground
circuit prove that both of these circuits are good.
A check of the TPS signal wire with the TPS disconnected shows the same 5.7 volts. The
technician now begins an inspection of the wiring between the TPS and the PCM and TCM to
no avail.
A replacement TPS does not cure the problem, neither does replacement of the PCM or
TCM.
The Switch Sense circuit in the Clockspring in the steering wheel hub has shorted to battery
voltage from the horn button circuit. When the Switch Sense Circuit shorts to the 12 volt
HORN circuit the TPS signal voltage is driven high and remains there as shown in Figure 1.
This is because the 5 volt reference voltage used by the Cruise “Switch Sense” circuit and
the TPS are shared inside the PCM.
Replace the Clockspring assembly. Once the Clockspring has been replaced, be sure to
check the sensor 5volt reference voltage at the PCM to insure that circuit has not been
damaged by the short to power. Also check the TPS signal range to insure the TPS has not
been fried.
03-23-2009, 07:48 PM
#3
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Year: 1999
Model: Cherokee
Engine: 4.0l
I totally agree.
(That's a little to technical for me, but I hate to see someone's thread die without any response.)
(That's a little to technical for me, but I hate to see someone's thread die without any response.)
Last edited by EvilBlackXJ; 03-23-2009 at 07:50 PM.
07-13-2009, 11:15 AM
#5
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Model: Cherokee
Question did this cause the car to stall on u all the time.i am having a problem with my wife 99 cherokee. the code says tps sensor or ecu changed the tps and nothing. was going to change the computer next. but was curious on what you are saying cause a while back her horn stopped working all of the studden. I need to get this thing fixed already. thanks
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