1999 Jeep Cherokee Sport wont shift into overdrive P1491

P1491 Rad Fan Control Relay Circuit An open or shorted condition detected in the radiator fan control relay control circuit. This includes PWM solid state relays.P1495 Leak Detection Pump Solenoid Circuit An open or shorted condition detected in the Leak Detection Pump (LDP) solenoid circuit.P0753 (M) Trans 3-4 Shift Sol/Trans Relay Circuits An open or shorted condition detected in the overdrive solenoid control circuit or Trans Relay Circuit in JTEC RE transmissions. Was MIL code 45. P0753 (M) Trans 3-4 Shift Sol/Trans Relay Circuits An open or shorted condition detected in the transmission 2-4 shift solenoid circuit (4-speed auto. trans. only).P0136 (M) 1/2 O2 Sensor Heater Circuit Malfunction Oxygen sensor heater element malfunction.

Aside from getting into an accident and having your wiring harness severely damaged, the other likely suspect is your PCM. These codes are not related to each other and indicate a much larger problem.

whats if its staying in a high gear and wont shift down or go into overdrive

this is an obd2 trouble code table, it can help you understand the meaning of code,
your dtc 1491 is to do with the rad fan relay, very common failure! As for the rear wiper button flashing it means theres a problem with your A/C
or heater controls.

P1491 Radiator fan relay control circuit
i remember someone else asking this question and another expert said it was behind the bumper ?? ,right looking in the dreaded haynes book and its right side ,no thats a 98 model a 99 model is left side next to vacumn tank ,earlier model its under behind the battery

It will shift out of overdrive upon increasing throttle , pulling hills and so on. Your overdrive probably kicks in around 35 to 45mph and kicks back out as you increase throttle. Electrically controled speed sensor to control the response. Overwise the engine would bog down to a stall. Over drive is just that. It changes the gearing ratio to over drive meaning less then final gear 4 to 1 down to 4 to 3 etc more direct drive ratio to lessen consumtion of fuel with less stress on engine. Have shift speed sensor adjusted. Don't drive in overdrive in city if most driving is under 45mph

Correct

Figures...I'd use 2&3 as b&c Open reading means that with the meter set to ohms and turned on, the meter should read the same connected to the terminals as it did before you connected it.

check oil level when hot with engine running and shift in reverse

Check the adjustment on the brake switch. If the brake switch is not seated properly it will engage when hitting bumps and tell the tranny to come out of overdrive.

My 97 Jeep Grand Cherokee was doing the same thing. I changed the TPS ( Throttle Position Sensor) Now it is great goes into overdrive fine. It is really easy to change.