My temp gauge went out in my 01 Grand Caravan and now I run (at times) at 230 degrees...I put a aftermarket sunpro gauge in and as a result, I've got nothing telling the radiator fans to kick on. I am wondering if my trans fluid is getting a little hot too and causing some smoke under the hood. Either way, I looked in the fuse box under the hood and did not see any extra spots for extra accessories. So I need to wire my stock fans to a switched location. Any ideas? I'd much rather have them on all the time than not at all!

 

The aftermarket sells relays and connectors that you can mount to the fender or wherever. The fans run off an input from the coolant temp sensor. If that were bad, I can't imagine how bad your engine would run. Coolant temp is a huge input for that. 230 degrees is not out of hand for fan operation......

OPERATION

RADIATOR FAN OPERATION CHART

COOLANT TEMPERATURE</B> A/C PRESSURE</B> TRANSAXLE OIL TEMPERATURE</B> Fan Operation Speeds: Initial Max Initial Max Initial Max Fan On: 104°C (220°F) 110°C (230°F) Fan Speed Duty-Cycles (Ramps-up) from 30% to 99% 1,724 Kpa (250 psi) 2,068 Kpa (300 psi) Fan Speed Duty-Cycles (Ramps-up) from 30% to 99% 96°C (204°F) 111°C (232°F) Fan Speed Duty Cycles (Ramps-up) from 30% to 99% Fan Off: 101°C (214°F) Fan Speed Duty-Cycles (Ramps-down) from 99% to 30% 1,710 Kpa (248 psi) Fan Speed Duty-Cycles (Ramps-down) from 99% to 30% 89°C (192°F) Fan Speed Duty Cycles (Ramps-down) from 99% to 30%

 

That chart didn't come out very well, but it says that 220 is normal fan on temp but under circumstances it can wait up to 230. Smoke under the hood could be steam from condensation on the radiator. Tranny might need a service.

 

It is not an aftermarket fan, it's the OEM...never been changed. The fan runs off the coolant temp sensor--yes, I had to plug that back in and leave it hanging out of the block. Yes, the engine runs terrible when it is not plugged in, as a matter of fact, it wouldn't start at all. It's the temp gauge in the cluster that's bad. When I took the cluster out and moved the gauge needles with my finger, the temp gauge was the only one that had resistance and didn't move as freely as the others. Also, when I do the cluster self-test, that gauge is the only one that doesn't move. So if the coolant temperature sensor is not in the manifold, it can't tell the fans to turn on, correct?

The smoke, I am not sure what that is, but it does smell of...I can't really tell, trans fluid or maybe coolant. The trans was rebuilt some 30k miles ago. When I take the dipstick out, it doesn't smell like burnt fluid. When I dirve the thing, see smoke, then get out to see where the smoke is coming from, I don't see where it is coming from...it doesn't really billow out.

And one last thing...perhaps for another thread. I am only getting 15.5 mpg. The normal for me in that van has been 19 average combined. I have checked everything that would be the normal culprits (tune-up stuff, tire pressure, air filter, etc.). Any ideas on that?

 

Have you considered pricing a cluster from a salvage yard so your gauge will work and you won't have to modify anything?

This is why your gas mileage is bad. I'm surprised you're getting that much. CTS is an input to PCM, it really comes into play for fuel trim.

 

Well damn...I didn't even think about that!!! This is actually the third cluster I have had.

So, even with the sensor plugged in like its supposed to be...if the gauge is reading low all the time/not working, would effect the the fuel economy? Because even with it plugged in, I was getting around the same MPG. If this is the case, then when you consider the price of gas, it wouldn't take long to pay for ANOTHER cluster.

 

what he said, I second that. As long as it's just the gauge, put the coolant sensor back in and fix the gauge.

 

Just reinstall the sensor into the block. The computer doesn't care if the cluster is working or not and should switch the fans on regardless of the cluster. These motors need to run hot so 220-230 is not unusual.

 

My concern was just that if it overheats, I can't tell. If the coolant area of the gauge doesn't work, will the check engine light come on if the van decides to overheat?

And, plugging it in won't fix the low fuel economy issue...as the gauge has not been working for quite some time and I have been getting terrible fuel economy since well before I took the temp sensor out.

 

Yes, the CEL will come on but only if the sensor is installed in the block.
You really have to reinstall the sensor for a few reasons one of which is fuel mix. Right now the engine thinks it's cold and will run in an open loop which is a rich fuel mix. Over time this will screw up the catalytic converter if it hasn't already. A partially plugged converter will screw up mileage big time.

Now to go back to your original question, find the fan relay and supply power to pin 85 or 86 of the relay. This is the relay coil. Find out which one is the ground and power the other. You need a really light gage wire because the coil draws very little power and space is important. Wrap the wire around the correct pin and push it back into its socket. Now find another relay, like lights, that is switched on from inside the car and wrap the wire around relay terminal 87. So now if you switched on your lights, the fan will come on.