Delayed engine shutdown

[wayne pick]

After installing a fan driven aux trans oil cooler my engine keeps running for about 10 seconds after I turn the key switch off. I reversed the polarity on the wires to make the fan run backwards, As per derale's instructions, this can be done. I know running a DC motor backwards it becomes a generator, like dynamic braking on a locomotive. Could the motor be feeding back current keeping the IP solinoid energised untill it stops spinning?

 

[doghead]

Where did you supply the fan with power from? If you simply tapped in at the pink wire on the IP, then yes.

 

[wayne pick]

Hea doghead, I used one of the three ign controled terminals on the left side of the fuse box. I also wired the converter lockup controller for the trans on the second of the three terminals. The controller has a reostat to control lockup sensitivity, Could that have anything to do with it? I will reverse the wires back on the cooler fan to see if it changes anything and turn off the controller before shutdown.

 

[doghead]

Is the fan on whenever the key is on? No temp sensor?

You could add a diode, or add a relay, to fix this, if that indeed is the issue.

I'd disconnect the fan and be sure it isn't just a bad shutoff solenoid.

 

[patracy]

Still has the manual fan though as well right? The engine's fan is still pulling air through the electric cooler causing it to act as a generator. It only take 9vdc to keep the solenoid open on the DB2 pump.

If you wish to keep it wired like you have it, a diode is the only way to fix it. A relay could still have the potential to remain energized.

 

[doghead]

It would be interesting to try shutting off the truck, with the headlights on.

 

[Cucvnut]

would it not shut off DH ?

 

[doghead]

No, it might shut off faster/like normal.

 

[deuceaid]

diode on the fan motor ( with proper heat sink to handle the amperage)

 

[doghead]

A relay could still have the potential to remain energized

If he used a relay that was supplied with 12v+(constant supply) and triggered the relay with the keyed 12v+, it would work.

Adding a diode is much more simple.

 

[Cucvnut]

Ah makes sence

 

[wayne pick]

M1031 late engine shutdown

No supplied relay w Derale cooler, strange right? I plumbed the cooler as a stand alone setup deleting the radiator cooler thinking this might help cool the engine in hot weather and simplifing the install, no hot trans oil running through it. I may use it as a power steering cooler later. Derale suggests not placing the cooler in front or behind the radiator, restricting airflow. I placed mine under the flatbed that was installed by the previous owner. I ran 3/8 brake line along the right frame rail to the cooler wiring it to the ign terminal on the fuse box with no thermostat switch. key on, fan on. It was so darn cold this morning, 14 deg I was not about to fool with it along feeling like I got hit by a bus after installing the trans by myself on Friday. Guess ill try a relay and a diode. not sure how to wire the diode, through the pos lead I would amaginge. I can wire up simple stuff like lights ect so excuse my wiring ignorence. Thanks guys for your help. WP

 

[deuceaid]

the diode only works one way and only has 2 terminals, so if the fan wont run,, then reverse the diode. You could get one of these and mount it somewhere, then just run power thru one of the ac terminals and the hot off of the positive terminal,,, most of the time there are rated for 20-40 amps

this is a bridge diode and has 4 diodes built into it

 

[doghead]

Any resolution to this, yet? How'd you decide to fix it?

 

[wayne pick]

Hea doghead, I ended up just running a switch to it for now. I switched the wires back to run the fan in the right direction, no joy, still ran after i turned off the keyswitch. I'll put a diode on it as you suggested when the weather gets a little warmer this spring. Had other issues with it lately, threw both alt belts last week and have to replace the fuel sender this week. BTW I got that survey page again when logging on just now, have not seen that in months. Thanks, WP