Limp mode Ig elec fuse is blowing could this cause the limp mode

IG /ECU fuse blows.
IS FUSE IN THE CAB OR ENGINE BAY?
JUST ONE FUSE? NO AMPS TOLD TO HELP ME,
no ENGINE told (4.0L v6 or 4.7 v8



the service manual on pages for PCM schematics clearly shows all things on that fuse to cause it to blow (i must assume correct fuse is there)

i am reading it to you now.

THE USERS MANUAL IS HERE (LOST?)
493 PAGE IS FUSES./
PAGE 494 SHOWS IT AS

. ECU IG 5A:
Anti?lock brake system,
vehicle stability control system
,multi-plex communication system ,
tire pres-sure warning system



USERS GUIDE
https://assets.sia.toyota.com/publications/en/om-s/OM34458U/pdf/OM34458U_edited.pdf


TO FIND THE SHORTED MODULE IF NOT WIRES SHORTED
PULL TPMS MODULE (TIRE PRESSURE)
THEN PULL , ABS CONTROLLER NEXT
AND IF STILL BLOW THE FUSE THE MUX PARTS MOST BE TRACED OUT

check is a/t control module. Personally i would take it transmission shop and have it looked at.

Whatever accessory or system is powered by fuse #21 has a short. It only blows when the ignition is turned on because no power goes to the fuse with the ignition off. If your transmission is in limp in mode, you need to have it checked. You don't mention make, model, or year vehicle, but your car may have a separate transmission control module (TCM); in any case see if you have any codes that indicate if there is a problem with the transmission. The O2 sensors have nothing to do with the transmission being in limp in mode, and I doubt that they are connected directly to the fuse. Most O2 sensors get their power through the PCM.

The only reason I can think where a fuse would be used for 02 sensor is the sensor heater circuit, maybe circuit is shorted to ground?
I need year--make--model??

Most limp modes are caused by transmission faults but can be caused by engine sensors and blown fuses. If your car is in limp mode the fault will be stored in the ECM.
You need to read the fault codes stored in your ECM to know which sensor has caused this problem. You didn't say what model vehicle you have and it would take a number of hours to list all the possible codes and reasons.
Get someone with a code reader for your model vehicle.

you might want in this case try a higher rating fuse, example is if the fuse is 15 amp rase it to a 25 amp fuse,try not to go over 40 amp if possible,if that still blows it is more than likley a shorted switch or a bad relay causing the overload or short. after the fuse change an still a problem chech the relay for the break lights next,these are located in the engine compartment and on some models in the trunk,good luck,Gary

You need to find out the transaxle strategy for going into
limp mode
You need a trans shop or a dealer
Have it towed on a rollback ,not flat towed or driven

The speed sensor is probably the root of your problems. Likely the reverse switch wiring is routed through the harness for the sensor. That could also be the reason it goes into limp mode. Change the sensor and see if all problems are resolved. Good luck.

FUEL PUMP MORE LIKELY WORN OUT SHORT OUT.BESURE REPLACE FUEL PUMP WIRES IF FUEL PUMP HAS TO BE REPLACED.CODE SCAN FOR ECU FAULT. IF FUEL FILTER STOPPED UP FUEL PUMP WILL SHORT OUT.

Which fuse is blowing and When it goes into limp have you had it scanned for codes. If the TCM goes into limp then it will have a code in the computer memory.