oe electric fan does not go on

R

revmeup

NAXJA Forum User

Location

Reno NV

• Jul 3, 2010

• #1

91 4.0 auto

OK............so if I check the sensor with my ohm meter it checks out ok. And I checked continuity from the fan to the relay........all good. And I can make the fan come on when I close the sensor circuit. The fan also comes on when the ac or defroster is on. It just wont come on when it gets hot (210) and up.

Any ideas?

 

joe_peters

NAXJA Forum User

Location

Grants Pass, OryGun

• Jul 3, 2010

• #2

Ok, at what temp doe the fan switch complete the circuit?

 

Frank Z

NAXJA Forum User

Location

Colorado Springs

• Jul 3, 2010

• #3

218 is the temp. that the PCM needs to see before the fan circuit is energized.

 

joe_peters

NAXJA Forum User

Location

Grants Pass, OryGun

• Jul 3, 2010

• #4

Frank Z said:

218 is the temp. that the PCM needs to see before the fan circuit is energized.

Click to expand...

Not sure the PCM controls fan operation on the 91, but I could be wrong--its happened before.

 

Frank Z

NAXJA Forum User

Location

Colorado Springs

• Jul 3, 2010

• #5

It does, the 91 is an OBD1 HO motor.

But you knew that already.

 

ehall

NAXJA Member

NAXJA Member

Location

Southern Maryland

• Jul 3, 2010

• #6

Frank Z said:

218 is the temp. that the PCM needs to see before the fan circuit is energized.

Click to expand...

Yeah the fan shouldn't come on until the needle is about halfway between 210 and the 3/4 hash marks. Right now the fan comes on with the A/C so that means the activation circuit is working.

 

J

JoJoDaKilla

NAXJA Forum User

Location

Oak Ridge, TN

• Jul 3, 2010

• #7

I wired mine into the rear wiper switch to cut on. Looks factory and it works.

 

in4aride

NAXJA Forum User

Location

Montrose

• Jul 3, 2010

• #8

ya just wire to a switch

 

M

matttaylor1976

NAXJA Forum User

Location

Grass Valley, CA

• Jul 4, 2010

• #9

Check the temp sensor in the radiator. Simply unplug the connector to the sensor, and short the connector that runs to the pcm. if the fan kicks on, the sensor could be bad.

I wired a toggle switch from those wires to fool the pcm into kicking the fan on whenever i feel the need.

 

R

revmeup

NAXJA Forum User

Location

Reno NV

• Jul 5, 2010

• #10

Thx for all the feedback!!!!!!!
did some more playing with it..............fan comes on but gauge shows 235. Next I will confirm the actual water temp in the t-housing to be sure it is the same as the gauge. Not so sure the gauges are accurate. I have several new sensors for the 91 xj HO. If the sensor in the t-housing now is triggering at an actual 235 or close I will switch it out and try one of the others I have to compare and if the results are similar I will look for other sensors with lower trigger on levels.