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Hello,

I have 98 Dodge GC with 200k+ miles.

Recently noticed that the car was overheating. Redline but only really during non-highway driving not constantly, seems to come off the redline a bit then go up from the center. Not in the evening for example (in SJ, CA the nights can be cool).

As an example drove the car with 5 people during day with AC on the highway and no problem. Took an exit and putted around some residential streets and the temp started to creep up.

Checked coolant level - NP. Noticed that the fans are not turning when the car was overheating and when the A/C was on (the electric fans cooling the radiator). Could be that ... then .... on a unrelated day the windshield wipers came on. Can't turn those puppies off now. Driving with them running in full CA summer is weird so I pulled the fuse which stopped that.

Trying to exorcise the daemons here.

I know that the fan could be the relay that has been talked about here previously.

Can the wipers being on all the time all of a sudden and the fans not running be related ? Some controller issue or something ?
 

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Interesting faults you're presenting! As you've said, most of the time the fan relay is the culprit and requires replacement. The relay is under the left front head light area if you're doing the repair yourself. A decent new relay will have a heat sink and some heat transfer compound for installation. Regarding the rad fans you might want to have a look at the coolant temperature sensor that sends signal to the Power Train Control Module to start the cooloing fans. Try and give the rad a good clean out flush as well. The relay testing thing can be tricky some times as it will show voltage but will not activate under load. There could be an outside chance the fan motors are dead but I wouldn't think that is the problem.

The wiper issue is a good one. Perhaps a park switch that's fused in the on position. If this was the case you would have to replace the wiper motor as the park switch module is integral to the wiper motor. You could try pulling the relays in the power distribution center (PDC) under the hood and give them a good cleaning or even replace them if a relay happens to be fused on and doesn't release. They are the relays right beside fuses 23, 24, 25 and 26 in the PDC in the line of relays 2nd and 3rd positon up from the front of the van. The "wiper on" relay is beside fuses 23, 24. There is a block diagram on the underside of the PDC cover. Hope that covers the location. When the wipers are on have you got any speed control at the switch on the column? Do the washer motors work when activated by the column switch? This is the opposite of a problem that a lot of people experience. Let us know what you discover. It is a great help when people post their fix.
 

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Discussion Starter #3
Interesting faults you're presenting! As you've said, most of the time the fan relay is the culprit and requires replacement. The relay is under the left front head light area if you're doing the repair yourself. A decent new relay will have a heat sink and some heat transfer compound for installation. Regarding the rad fans you might want to have a look at the coolant temperature sensor that sends signal to the Power Train Control Module to start the cooloing fans. Try and give the rad a good clean out flush as well. The relay testing thing can be tricky some times as it will show voltage but will not activate under load. There could be an outside chance the fan motors are dead but I wouldn't think that is the problem.
yes, i'll follow the instructions given on this and see where this will lead to.


The wiper issue is a good one. Perhaps a park switch that's fused in the on position. If this was the case you would have to replace the wiper motor as the park switch module is integral to the wiper motor. You could try pulling the relays in the power distribution center (PDC) under the hood and give them a good cleaning or even replace them if a relay happens to be fused on and doesn't release. They are the relays right beside fuses 23, 24, 25 and 26 in the PDC in the line of relays 2nd and 3rd positon up from the front of the van. The "wiper on" relay is beside fuses 23, 24. There is a block diagram on the underside of the PDC cover. Hope that covers the location. When the wipers are on have you got any speed control at the switch on the column? Do the washer motors work when activated by the column switch? This is the opposite of a problem that a lot of people experience. Let us know what you discover. It is a great help when people post their fix.
I had just tried playing with the relays as you suggest.

They all seem to be good. I swapped the wiper relay for the lights relay and got the same results. So I don't think it's the relays.

An interesting observation to this puzzle: When I pull out the relay (or fuse) for the wiper blades, turn off ignition, and turn off the wipers then re-insert the relay (or fuse) the wipers are not moving - everything is in the OFF position.

When I turn the wipers ON i cannot turn them OFF.

Furthermore, while the wipers are moving, and I just pull out the relay (fuse) they stop. They continue when I insert the relay (fuse).

Here comes the interesting part: I remove the key from the ignition (while the relay is out). Then I re-insert the ignition key, make sure the wiper switch is off. Re-insert the relay. Nothing. Turn the wiper switch on for a second and the blades turn. Turn it off they turn off. However, if I let the wipers cycle to their normal off position then they once again unstoppable.

Crazy.

Well at least it's a ghost with a sense of humor. Mess with the wipers during summer when I don't need them. What's in the winter ? All the power windows will stay in the open position ?

Thanks for the reply.
 

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It could be the multi function switch on the steering column. That's why I was asking about your washer functions and whatnot. How about disconnecting the battery then undo the connectors going to the junction box under the driver kick panel and give them a good cleaning with no residue electronic contact cleaner. The BCM is involved with the wiper function and there may be some minor corrosion. It can't hurt if it hasn't been done in the life of the vehicle. There are quite a few posts suggesting "multi function switch" on the column. It makes sense. Unless there is some sort of problem with the CCD buss data link I wouldn't think the problems are related.
 

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It could be the multi function switch on the steering column. That's why I was asking about your washer functions and whatnot. How about disconnecting the battery then undo the connectors going to the junction box under the driver kick panel and give them a good cleaning with no residue electronic contact cleaner. The BCM is involved with the wiper function and there may be some minor corrosion. It can't hurt if it hasn't been done in the life of the vehicle. There are quite a few posts suggesting "multi function switch" on the column. It makes sense. Unless there is some sort of problem with the CCD buss data link I wouldn't think the problems are related.
There is 2 speed control of the wipers. The washer fluid works with no issues. There just appears to be no OFF ;-)

At least once the ON has been performed.

I'll give a whirl to this suggestion and report back.
 

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...thought I'd add a thought about the cooling fans not functioning and overheating when the AC is on. There is a pressure transducer on the fluid line that also sends a signal to the PCM for fan operation.
 

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Replaced the relay tonight. Drove around with the A/C on at like 10pm but here in CA it's pretty cool already. Could not get the fans to turn on ... but the temp stayed right in the middle.

I tested the fans by connecting them to the battery ... they do spin. So it could be a relay ... could be something else.

Any wisdom to as to how to test the (old) relay ?

Here is the picture of the relay location:

 

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Nice picture of the relay location. That will help a lot of folks.
Perhaps let the vehicle idle for awhile with the AC on full and see if the fans come on. They should come on fairly quickly. The coolant temperature sensor seems to be working if you've got the temperature gauge working. The only other things I'm aware of are the potential for the PCM to fail and not activate the relay. I'm not sure what occurs if the pressure transducer on the AC system is not working properly but you'd think the fans would activate with high coolant temperature. We don't want the problem to be the PCM but it is in the circuit.
 

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You might want to look in on a thread by "LexRex" -"Cooling Fan Problem" He's got the same thing going on. He's starting to think PCM fault.
 

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At this point it certainly wouldn't hurt to get a professional scan done on your Control modules to see if any codes are registered.

I thought I would post some reading for you about the AC and fans issue. These are exerpts from Forum contributors. If your refridgerant is low there may not be enough pressure to activate the AC pressure transducer to run the fans in high speed. There is info below so you can test your transducer just in case.

The rad fan relay is a solid state fan relay is attached to the left frame rail near the lower radiator support. If you remove the air filter housing you will find it.
If you locate the relay and unplug the connector you can test to see if you have battery power to the gray wire. If you do jump the gray wire to the dark green wire the fans should turn on.
The radiator fan runs at a variable speed depending on coolant temperature and A/C system pressure. The radiator fan circuit contains a Solid State Fan Relay (SSFR) Refer to the model year service manual wiring diagrams or an appropriate circuit schematic from other source.
A 5 volt signal is supplied to the SSFR. The PCM provides a pulsed ground for the SSFR. Depending upon the amount of pulse on time, the SSFR puts out a proportional voltage to the fan motor at the lower speed. For instance, if the on time is 30 percent, then the voltage to the fan motor will be 3.6 volts.
When engine coolant reaches approximately 102°C (215°F) the PCM grounds the SSFR relay. If engine coolant reaches 207°C (225°F) the PCM grounds the high speed ground relay and high speed fan relay. If the fan operates at high speed, the PCM de-energizes the high speed relay and high speed ground relay when coolant temperature drops to approximately 101°C (214°F) When coolant temperature drops to 101°C (214°F) the fan operates at low speed. The PCM de-energizes the low speed relay when coolant temperature drops to approximately 93°C (199°F)
Also, when the air conditioning pressure switch closes, the fan operates at high speed. The air conditioning switch closes at 285 psi ±10 psi. When air conditioning pressure drops approximately 40 psi, the pressure switch opens and the fan operates at low speed.
The rad fan relay has usually been the problem on any vehicles that I have worked on when there is power to the gray wire. Your AC needs to have the fans working in order for it to cool properly.



Radiator Fan & A/C Pressure Transducer
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Temp readings are from ECT (engine coolant temp sensor) Pressures are from A/C pressure transducer
Fan low speed 104 C (220 F) 1,724 Kpa (250 Psi)
High Speed 110 C (230 F) 2,068 Kpa ( 300 Psi )
Fan turns off at 101 C (214 F ) or when Pressure drops below 1,710 Kpa (241 Psi ) Low speed is at 30% speed and will increase from 31% up too 100% duty cycle depending on the temp or pressure inputs.

Transducer Voltage 0 Volts = transducer faulty or no voltage from PCM
.150 to .450 volts = Transducer Good/low pressure cut out condition
.451 to 4.519 volts = normal operating condition
4.520 to 4.850 volts =Transducer good High pressure cutout condition
5 volts = Transducer Faulty
Wire Colors Dark Blue = Switch output to PCM
Violet/ White tracer = 5volt supply from PCM to transducer
Black/ Lt Blue tracer = sensor ground
Hope this helps and clears up some problems for those trying to fix fan and A/C problems. Hope it makes sense.
Fan comes on with gauge at approx. 9/16 to 5/8 gauge reading.

Keep us posted with your progress.
 

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On 3rd gens, the wipers tend to not shut off because the park switch tends to go bad so it doesn't know when to turn off.
 

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Replaced the relay tonight. Drove around with the A/C on at like 10pm but here in CA it's pretty cool already. Could not get the fans to turn on ... but the temp stayed right in the middle.

I tested the fans by connecting them to the battery ... they do spin. So it could be a relay ... could be something else.

Any wisdom to as to how to test the (old) relay ?

Here is the picture of the relay location:

Did you get a new connector w/ wires that need to be spliced in with the relay? I replaced the relay on my '00 and at first just connected the new relay to the old connector. By sheer dumb luck, I looked at the wires a few inches away from the connector and one was basically copper dust. So I spliced in the new wires/connector and WOW, fans that work. Who knows, I might have gotten away with just fixing that wire to get my fans back.

-Andrew
 

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Thanks for posting about your corroded fan harness. This is a good point and happens all too often.
 

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I believe I might have found what your issue is, I was gutting my 1997 Dodge Caravan as its going to scrap tomorow, I removed the windshield washer resivar (csws) as I wanted it and the pumps, The min I cut the wires for it (one at a time) the wipers started to kick on and will not shut off, Unless I tried what you did to get yours off. Take a look at the wires going to the washer pump and the connections, pass side under the fender skirt
 

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Sorry I dropped off for a week without update ... but my wife told me that the driver window was down on the car and it was unlocked ... that was a window regulator that went bad and somehow the glass dropped into the cavity.

I replaced the window regulator just this weekend and took the car for a drive.

I ran it with the A/C on and when I got home opened the hood and noticed the fans were turning!

Having replaced the relay I am assuming that was the problem. Since I live in the bay area I am a little less inclined to believe it was poor contacts since we really don't get very much "bad" wheather and there is comparatively very little moisture in the air. Things just don't rust as fast as in the other parts of the country [when i moved here a mechanic pointed out about my are then that it was not a a CA car] - but who knows. At least one problem solved.

I have not yet figured out the wipers issue. Thanks to all that had helped and pointed out various approaches. I will investigate (we are still 2-3 months away from rainy season) :)
 

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What Andy and RIP are saying is that you would have to replace the wiper motor if the problem is the wiper "Park Switch" because the switch module is integral to the wiper motor. I was suggesting the "Multi-function" switch on the steering column. Your choice! It may be easier to illiminate the multifunction switch first if you're going to throw parts at it. Obviously if the problem continues then it would most likely be the park switch in the wiper motor. Lots of cases to suspect either. The Body control module is involved with the intermittent wipe functions relative to vehicle speed and whatnot controlled from the column switch. If the wipers reseat themselves this may be the Multifunction switch. Let us know how you make out with this as it can help others that are having this same issue.
There doesn't seem to be very many definitive posts with fixes for this problem. Good to hear your rad cooling fans are working. So I'm assuming from your post that the call on the rad fans was probably a bad relay.
 

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Once again:

I believe I might have found what your issue is, I was gutting my 1997 Dodge Caravan as its going to scrap tomorow, I removed the windshield washer resivar (csws) as I wanted it and the pumps, The min I cut the wires for it (one at a time) the wipers started to kick on and will not shut off, Unless I tried what you did to get yours off. Take a look at the wires going to the washer pump and the connections, pass side under the fender skirt
 

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If you read back in the thread you'll see that Merlin is reporting that there is no issue with the windshield washer on his vehicle. If there was a fault in that circuit the washer motors would probably not be functioning. If you're going to strip down parts from your van it might be a good idea to disconnect the battery before proceeding.
 
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