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Radiator fan won't turn off when car is shut off


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Hey everyone,

Fixing up some more things on my '90 TC since I've got it out of storage. The last couple years when I've driven it, sometimes when I shut the car off, the radiator fan keeps running. A couple times, it's ended up draining the battery dead. It doesn't do it all the time, but when it does, if I hear it, I have to unplug the battery cable to avoid a dead battery until I get back in to drive it again, at which point I plug it back in. It's a pain because my hood gas struts are shot, and that baby is HEAVY to lift by yourself while also re-hooking-up the battery. Have no idea what would cause this to happen. Even replaced a couple relays thinking that might be the cause. Still happens. Anyone else ever have this happen, or have any suggestions for what it might be and how to fix it?

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Sounds like the auto shut down relay isn't shutting down, usually the relay, but these cars are getting old enough that it could also be a sloppy ignition switch. Next time it happens flip the key from Off to ACC to Off to ON to OFF several times and see if it makes a difference.

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39 minutes ago, Digger914 said:

Sounds like the auto shut down relay isn't shutting down, usually the relay, but these cars are getting old enough that it could also be a sloppy ignition switch. Next time it happens flip the key from Off to ACC to Off to ON to OFF several times and see if it makes a difference.

 

To make sure I've replaced the right relay, do you happen to know where the relay is located? I think I've replaced the right one, but want to make sure. I'll definitely try to flip the ignition back and forth next time to see if that makes a difference as well.

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I have had problems with my rad fan relay. I have replaced it 4 times in last 2 years for fan not coming on(overheating). When temp gage gets up to 3/4 I have to go under the hood and tap the relay with screw driver handle & fan comes on. It is driving me crazy. Tried fan relay's from 4 different companies. Anyway to identify which relay is for fan, there are 2 relays on left fender area behind the shock tower, one for fan, & one for A/C clutch. The fan relay wires on plug end are 14GY, 14LG, 18WT, 20DB/PK* .  A/C relay wires are  14GY, 14DB, 20DKBL/OR*, 20DKBL/OR*. This info is from my TC service manual. Also if anybody has any suggestions as to why I have to hit my rad fan relay to energize it I would like some help.   Thanks, Bob Barrow

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Thanks Bob and Digger. Next time it happens, I'll make sure that I've replaced that relay in case I haven't done that one yet, and I'll try the ignition trick as well. Hopefully I can get it fixed. Not sure about why the screwdriver trick would work for you Bob if you've already replaced the relay. Sometimes, you've just gotta do what works with these cars, haha. Hopefully someone else may have a better idea why that would make it work. Lose connection somewhere maybe?

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On May 26, 2016 at 10:39 PM, mytc05 said:

Digger wrote; Sounds like the auto shut down relay isn't shutting down, usually the relay, but these cars are getting old enough that it could also be a sloppy ignition switch. Next time it happens flip the key from Off to ACC to Off to ON to OFF several times and see if it makes a difference.

To make sure I've replaced the right relay, do you happen to know where the relay is located? I think I've replaced the right one, but want to make sure. I'll definitely try to flip the ignition back and forth next time to see if that makes a difference as well.

It really makes me hesitate to even attempt to help here on this forum.... I see people write so many things that are totally incorrect. As you all have seen, I have taken heat for pointing out problems on some owners cars where I was totally in the right, but the reader misinterpreted my remarks.

 

It makes me laugh when advice is given and it steers someone in the totally wrong direction.

Do the 'experts' here not check their sources, such as the Chrysler Factory Shop Manual, the only book to reference these cars in?

 

I will simply say this, the screwdriver trick works largely because the Fan Relay Contacts are apparently sticking together when the signal to engage them, is removed (disconnected). That signal comes from the SMEC.

To say that the fan may continue to run due to "the ASD relay isn't shutting down" would also mean that the engine would not shut off!

The ASD Relay controls 2 major 'things'. Those are; BATTERY + POWER to the Ignition coil, to produce spark, and BATTERY + POWER to the electric fuel pump in the fuel tank to supply fuel for the engine to burn. The ASD relay also gives BATTERY + POWER to the SMEC so that the sensory circuits can function.

Since this problem has continued over a period of time and possibly through the life of several fan relays, my thoughts shift to the fan motor itself. It is A POSSIBILITY that the fan motor is drawing an excessive amount of current in order to start rotating, therefore creating a larger than normal electrical arc at the time the contacts are closing. This will burn the contacts and even possibly "FUSE" the contacts together.

If you can, check the current draw on the fan motor or just replace the fan motor as a precaution.

 

Edited by Hemi Dude
spelling correction (see edit history)
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To be honest guys, my Dad is the real mechanic when it comes to working on my car. He used to be a Chrysler mechanic and Service manager for years. So, he usually helps me with these fixing projects on my TC, but I like to run things by everyone here on the forums first since you guys have experience with all the intricacies and little tricks with fixing our unique cars and have probably done each of these projects. We do have a service manual as well, but since I'm trying to diagnose this issue and be able to deal with it if it happens while I'm not near my Dad for help, I just wanted to check with you guys. That way, when it happens, I can get a better idea of what's going on and let him know what we need to fix. So, as always, I appreciate you guys' help! Just have to wait and see when it happens again. Thanks again guys.

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This is to Hemi-Dude & Digger 14. My comment about using a screwdriver handle was to turn on the rad fan by tapping the relay. was because I have to watch the temp gage while driving (especially with A/C on)  & when it gets over 3/4 I have to stop & get ,open up the  hood & tap relay & fan comes on immediately. I  have checked all 4 terminals on relay with a volt meter & test light & everything is OK. I also checked all terminals on relay plug for corosion & sprayed with contact cleaner.  Any ideas?   Thanks, Bob Barrow. 

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34 minutes ago, Bob Barrow said:

This is to Hemi-Dude & Digger 14. My comment about using a screwdriver handle was to turn on the rad fan by tapping the relay. was because I have to watch the temp gage while driving (especially with A/C on)  & when it gets over 3/4 I have to stop & get ,open up the  hood & tap relay & fan comes on immediately. I  have checked all 4 terminals on relay with a volt meter & test light & everything is OK. I also checked all terminals on relay plug for corosion & sprayed with contact cleaner.  Any ideas?   Thanks, Bob Barrow. 

I will give you my personal, professional OPINION here Bob.

From what you write, it would seem to me that your problem is with the contacts within the FAN RELAY itself. This is a reoccurring problem with vehicles this age in general.

Imagine how many times that relay has engaged and disengaged over the years. Contact failure happens, just as it did with ignition points on older cars. They just don't last forever.

With all that being said, it would seem to me that you will need to replace the relay. It is the easiest for you to do and the least expensive. Once you let someone else get their hands into it, who is in the business of auto repair, you are at their mercy. You can find the relay at RockAuto.com  Here is just one relay available. 

AIRTEX / WELLS 1R1233 {Click Info Button for Alternate/OEM Part Numbers}  Info
 
 
 
 
Previous Image
1R1233__ra_t.jpg
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$8.31  
 
If you wish further help, we are here for that. I should have asked, "What year model is your TC?" The relays can be different between the 89 and 90-91 year models.
Edited by Hemi Dude
a little more information added. (see edit history)
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Thanks for the quick reply. I should have mentioned that the car is a 1990 3.0 litre. I have replaced the relay 4 times from 4 different suppliers. The part # i have been using is 5233212 . The reason I monitor the temp gage is that it will overheat if I don't tap the relay. The car has only 30000 miles on it.   Bob

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14 minutes ago, Bob Barrow said:

Thanks for the quick reply. I should have mentioned that the car is a 1990 3.0 litre. I have replaced the relay 4 times from 4 different suppliers. The part # i have been using is 5233212 . The reason I monitor the temp gage is that it will overheat if I don't tap the relay. The car has only 30000 miles on it.   Bob

OK Bob, I guess it is time to get down and dirty. You wrote; " I  have checked all 4 terminals on relay with a volt meter & test light & everything is OK." That really does not tell me anything.

With the relay disconnected from the wiring harness connector, which terminals give a reading of 12V? I need the colors of the wires or a photograph.

With the relay connected to the wiring harness connector, With your VOLTMETER, please give me the voltage readings you get on terminal C25, that is the one with the 14 gauge wire that is LIGHT GREEN. This is the 12V + lead to the radiator fan. It should be energized both when the cooling fan is to be on, with the engine running and having reached 'fan-on' temperature (1)  just for engine cooling, WITHOUT THE A/C BEING ON in any way,

AND (2) every time the A/C clutch engages with the A/C turned on, engine running. If you have to tap on the relay to get a reading/response, let me know.

 

HAVE YOU TAKEN THE COVER OFF ANY OF THE RELAYS YOU HAVE REPLACED, to see if you can detect any defect within the relay? You have apparently experienced this problem for a long time without resolution.

When you write"I have replaced the relay 4 times from 4 different suppliers." Did you personally replace the relays or some repair shop? The more information I have the better I can resolve this.

As I have said before, "Electrical diagnoses of an automobile in not easily done long distance"

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Hemi, thanks for all the help. I am my own mechanic, so I do all my own work. I retired from Chrysler Canada after 43 years, 18 years ago. I was a service engineer which included writing service bullletins, working with chrysler mechanics on the hot line etc., Anyway I have checked the original relay and first purchased one by removing the cover & checking the contacts. Everything looked OK. I will give you  the voltage readings the next time I arrive home with problem.  I thought the rad fan came on if the A/C was engaged no matter what the engine temp was. Do you know if the voltage from the SMEC, Dark/Blue,Pink * is a ground, 5 volts or 12 volts? I know the Grey wire has 12 volts,& Lt, Green (to rad fan) has 12 volts after I tap the relay. I am not sure what the white wire (B1) is supposed to be. It shows on page 30 of wiring diagram tha it goes toB1 slice on page 66. Can't find that. Hope this helps you. I am out of options. Also I drove the car a couple of days ago(temp 91) after I squeezed real hard on relay to harness & for the first time it seamed to work. I was thinking about trying to squeeze wire end connections in the harness where the blades of the relay contact. I hope this does not make you think to hard>  Thanks again.   Bob

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39 minutes ago, EmmettTC said:

Was there a different FAN relay used on the turbos vs the V6?

There were various part numbers for different bodies ( K, E, Q, P, etc) during a model year, not specific to turbo / non-turbo. There were also various depending on year model.

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