Instead of shifting to overdrive trans goes from 1-3 then N. can i fix this with a shift solenoid? 2003 merc. grand marquis.

Probably a shift solenoid in the transmission.

sounds like a tcc issue in the transmission. some times it can be fixed with an ecm flash. often it is a bad tcc solenoid inside the trans. valve body.

I think you have a four speed electronic overdrive like my 94 merc.

I never had problems but I changed filter and fluid and added Lucas Oil Products - Transmission Additive 24 oz do not over fill.

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.

Hope it is a solenoid issue or your pulling the trans out
Try a trans shop
The shift solenoid should be accessible removing the tran pan
It is 14 years old so don't get you hopes up for a simple fix

about 7L to 8L .don't flush.

you will need the ****** rebuilt to fix that problem.. sounds like truck was driven in town with the overdrive on.. overdrive is for highway use only any in town driving in that gear will destroy it...

Not the Trans Filter
Not the Fuel Filter
Not just you

TPS Sensor --worth testing

Any number of shift solenoids or solenoid pressure
control pack -- could be an issue

Could & should be changing trans & power steering
fluids every 3 years & not over 30,000 miles, on those
fluids. That won't fix anything,but may help them last longer

Make sure you use Mercon V Fluid

If the Spark Plugs have over 60,000 on them, install new ones

If the front O2 Sensors are OEM & 100,000 miles -get rid of them

They had a lot of problems with the pressure sensors. I would replace the whole tail shaft because they had problems with them. You don't have to remove the trans to remove the shaft. Get one from the junk yard. Hope this helps leave comment.

I think rebuild try and service it if you find any lining material in the pan bad news