The old 3.9L truck has been running great. I just got back from a 150mile trip to my moms and found i have a code 17 and a code 35. Assuming it's not a wiring issue, do i just start replacing parts? Thermostat, rad cap, coolant sensor, rad fan relay, etc?
What would you guys do if you were to get these codes? Thanks!

 

Is yours a 2.5L I4? If not, that 35 may be suspect.

I'd first gun the thermostat housing to see how hot it's getting (with a non-contact thermometer) to see if it's getting hot enough and the sensor's off, or if it's colder than it should be.

Although, you may be able to judge from how hot the water gets with the cap off (DON'T OPEN IT HOT!! Open it, start the truck, and let the thermostat open.)

RwP

 

sorry bout that; mines the 3.9L

 

I can get to it tomorrow and test the thermostat like you said. simple place to start. thanks

 

Thermostat could be stuck open, or coolant could be low. 35 is a strange one however.
New thermostat and gasket is like $10,n too bad there

 

Does the 91 even HAVE an electric cooling fan?

 

thanks; i did idle the engine with the cap off and saw some bubbles, the coolant level rose a bit and it began getting warmer. Still, i think we'll change it along with the rad cap.
While i was idling the truck, the gauge stayed on cold. i'll drive it around tomorrow and see if it moves. code 35...i'll look but i dont remember any radiator relay in the black box along with the asd relay.

 

[QUOTE=HeyYou;3466085]Does the 91 even HAVE an electric cooling fan?[/QUOTE

surely not and that is what a relay would control i guess. so i'm like you on that code..strange

i thought the fan ran all the time but idk.

 

If it's belt driven, then yeah, it has thermal clutch on it, but, the fan is still spinning, just not expending a lot of effort to move air. (assuming the clutch is working properly. )

There might be an electric fan inside the shroud though, between the radiator, and the mechanical fan...... I know newer trucks have 'em, not sure what year that started. (I have a full sized truck, so, no experience there.....)

 

Only the 4bangers had the electric fan for the 1st gen from the factory; hence the 35 being a 2.5L only code for 1991.

According to http://www.dakota-truck.net/CODES/codes.html anyway. The 35 being a 2.5L only code, that is.

RwP