Hyundai F4A51 with ISS troubles

Aug. 25, 2014

Changing the sensor and cleaning the connector will fix the problem but if the hose leak isn’t addressed, it will only be a matter of time before this problem repeats itself.

Wayne Colonna

The other day I was visiting a shop located in Homestead, Fla., called WiWi’s Transmissions. Alberto Rivera, one of the techs there was working on a 2007 Hyundai Santa Fe. This vehicle was fitted with a V6 2.7L engine and the F4A51 four speed front wheel drive transmission.

It came into the shop due to intermittent failsafe conditions. A P0717 code was retrieved revealing a missing Input Shaft Speed Sensor (ISS) signal. In this case, intermittent losses of the ISS signal. ISS codes are not uncommon with these vehicles. 2006 and earlier vehicles P0715 was the code assigned for the ISS. 2007 and later it is now P0717.

This ISS is a 3 wire hall effect sensor which provides a 5 volt pulsed signal to the computer on the center wire. Ignition voltage is supplied to the sensor on one outer wire and ground provided to the sensor on the other outer wire (Figure 1).

Since there was an intermittent problem with the signal, Alberto removed the air duct and battery to do a visual inspection of the ISS (Figure 2). He already had a suspicion as to the cause of the problem as he had seen this problem several times before.

Both the ISS and OSS are located on top of the transmission. The OSS (Output shaft speed sensor) is located over the differential area of the case closest to the firewall of the vehicle. The ISS sits more near the middle of the case next to a cooling line and is buried in a trough area of the case (Figure 3).Once Alberto gained access to this area his suspicions were realized. The ISS was wet and the trough area it sits in contained a relatively good amount of water

pooling (Figure 4). Without much thought or attention, this water pooling could be misunderstood as rain water mixing with oil. But what is really going on is engine coolant dripping out past the clamp from the lower radiator hose as seen in Figure 5.

Changing the sensor and cleaning the connector will fix the problem but if the hose leak isn’t addressed, it will only be a matter of time before this problem repeats itself.