Code #9 in the HGS is the valve block control valve (Y3/1y2) in the valve body Verify that the alternator is not under or over changing. Check the alternator

Output at the battery post with all accessories on including the engine running, lights, heater, etc. 13.4 to 14 volts =’s ok. If the volts are less than 13.1 the charging systems is marginal, then do a voltage drop test, the reading should be 0.00 to 0.10which means the ground is ok. If more volts are present you have a bad battery ground. Check and clean the ground wires W1 main ground behind the instrument cluster, W16/2 and W16 on the firewall. Clean the connector contacts on the throttle potentiometer (TPS)

Clear the code, then drive the car at about 56MPH in position “4” release the gas pedal and immediately move the lever into the “D” position, the transmission should shift in to 5th. Then select “4” the transmission should down shift to 4th gear. Check for codes

Let’s verify we have no 5th gear. At 62MPH with a 3.69 rear “3” = 4300rpm, “4” = 3000rpm, “D/ 5th” =2200rpms. With a 3.46 rear “3” =4000 “4” = 2800 and “5” = 2100rpms.


Make sure you have the right HGS for that model car.

The 722.5 was an option.