Speed Odometer and Oil Gauge Drops

Odometer The instrument cluster receives odometer rolling count status from the PCM-engine computer and stores the mileage in non-volatile memory (NVM). When the instrument cluster fails to receive the odometer rolling count status for more than two seconds, the odometer display will show dashes.

HEC Dealer Test Mode
To enter the HEC Dealer Test Mode, depress and hold the instrument cluster SELECT/RESET button and then turn the ignition switch to the RUN position. Continue pressing the SELECT/RESET button (5 seconds) until tESt is displayed in the odometer. The SELECT/RESET button must be released within 3 seconds of the odometer displaying tESt to begin the dealer test mode. Depress the SELECT/RESET button to advance through the following steps until dtc is displayed. Depressing the SELECT/RESET button will display any continuous DTCs stored before proceeding to the next step.

All segments illuminated Illuminates all odometer segments. If any odometer segment is inoperative, INSTALL a new instrument cluster; REFER to Instrument Cluster .
Odometer Display Description GAGE Activates gauge sweep of all gauges, then displays present gauge values. Also carries out the checksum tests on ROM and EE. If the gauge sweep is inoperative, INSTALL a new instrument cluster; REFER to Instrument Cluster . All segments illuminated Illuminates all odometer segments. If any odometer segment is inoperative, INSTALL a new instrument cluster; REFER to Instrument Cluster . bulb Illuminates all micro-controlled lamps and LEDs (low oil pressure/high coolant temperature, low fuel, service engine soon, brake, low range). INSTALL a new bulb or LED as necessary. r Returns to normal operation of all micro-controlled lamps and LEDs and displays hexadecimal value for ROM level (used when requesting assistance from the hotline). If alternating flashes of FAIL and ROM level are displayed, INSTALL a new instrument cluster; refer to Instrument Cluster . EE Displays hexadecimal value for EE level (used when requesting assistance from the hotline). If alternating flashes of FAIL and EE level are displayed, INSTALL a new instrument cluster; refer to Instrument Cluster . dt Displays hexadecimal coding of final manufacturing test date (used when requesting assistance from the hotline). dtc Displays continuous DTCs. Pressing the SELECT/RESET button will display any DTCs stored before proceeding to the next step. enG Displays the English speed in mph. Speedometer will indicate present speed within tolerances. Display will show 0 if input is not received, if input received is invalid for one second or more, or if speed is 0. m Displays the English speed data (mph) received from the PCM via SCP Network. Displays the metric speed in kph. Speedometer will indicate present speed within tolerances. Display will show 0 if input is not received, if input received is invalid for one second or more, or if speed is 0. tAc Displays the tachometer data received from the PCM via the SCP Network. Tachometer will indicate present speed within tolerances. Display will show 0 if input is not received, if input received is invalid for one second or more, or if engine rpm is 0. FUEL Displays the actual A/D fuel level. The fuel gauge will display a filtered fuel level value. This filter will keep the pointer from moving suddenly or erratically. If the value displayed is between 0 and 20, the circuit is shorted. GO to Pinpoint Test D .

• 255=open send +/-0
• 232=Full stop +/-10
• 215=Full mark +/-10
• 178=3/4 mark +/-8
• 138=1/2 mark +/-7
• 93=1/4 mark +/-5
• 41=E mark +/-4
• 54="LOW FUEL" (0-59)
• 0-18=short (0-20 max.)

OIL Displays the code (0-255) for the oil pressure switch input to the HEC. Displays the oil pressure reading input to the HEC. Oil pressure gauge will indicate present oil pressure. Normal oil pressure (greater than 6 psi) will display a value between 000 and 176. A low oil pressure (less than 6 psi) or an inoperative engine oil pressure switch will display a value greater than 176. dEGC Display of engine temperature in Degrees C input from cylinder head temperature sensor. If the value displayed is -40C, the SCP message for engine temperature has not been received for more than 5 seconds. GO to Pinpoint Test E .

• 49 C="C" mark.
• 60 C=Normal band start.
• 120 C=Normal band end.
• 119 C=Temperature warning indicator ON.
• "-40" C=No SCP Message for 5 sec.

br Displays the brake fluid level input to the HEC. bAtt Displays the code (0-255) battery voltage input to the HEC. Battery voltage gauge will indicate present battery voltage.

• 93-102=6.9-9.1 volts (Low voltage)
• 115-124=8.5-10.7 volts (Norm band start)
• 215-225=15.8-18 volts (Norm band end)
• 230-241=16.9-19.1 volts (High voltage)

rhEo Displays the present hexadecimal value for the instrument cluster backlighting pulse width modulated (PWM) input to the HEC (used when requesting assistance from the hotline). rhi
rhS
rho PWM input duty cycle.
SCP hexadecimal dimming step (used when requesting assistance from the hotline).
Output driver counts in hexadecimal format (used when requesting assistance from the hotline). Cr Displays the present RUN/START sense input. Display will show -h with the ignition switch in the START position and -L with the ignition switch in the RUN position. ALtF Displays 8-bit hexadecimal value for alternate fuel level. Display will show a value between 00 and FF if the message is received. PA-PE7 Not used. GAGE Repeats test display cycle.
Turn the ignition switch to the OFF position or press and hold the SELECT/RESET button for 3 or more seconds and release to exit HEC Dealer Test Mode. If no DTCs related to the concern are retrieved, proceed to the Symptom Chart to continue diagnostics.

Check wirring for damage

Could be the Oil Pressure Sending Unit. I do recall GMC having issues with the instrument cluster on 2003's. Try slapping the dash when the gage reads zero.

CHECK GAUGE FUSE . CLUSTER ASSEMBLE FAILED

oil and fuel guages look as though they have had excess voltage applied to at some stage. these can be removed and sent to a gauge repairer. Printed circut board behind dash may have to be inspected and/or repaired. Speedo could be tested by removing sender and gear drive and spinning with cordless drill watching that you dont over speed and wreck the head unit. hope you have some success

They are designed to change as the motor changes speed. If you have 80 lbs. of oil pressure than you have very good oil pressure in your engine. If it gets higher than 80, I would talk to service dept. at your local dealer.

There are motors that move each gauge inside your dash called jumper motors. They go bad all the time in your year of car. There are companies that you can send your gauge cluster to and they will replace all of the motors for around 150 dollars. Or you can buy some on eBay and soder them in yourself.

Check the ground wire, could be corroded.

2 things come to mide off the bat loose or corroded ground or cluster going bad