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Hi I have a 2007 Chrysler 300 C, AWD,5.7L hemi with automatic climate control. so I have a problem, No power with key in the ignition and vehicle running, at fuse# 42 in the trunk power distribution fuse box. I know that the relay is what supply's power to fuse #42. What if relay is good and still no power at fuse #42 ?
I put a jumper wire in where the relay sat and I get power to fuse #42 and everything at the climate controls works, blower motor with all speeds,a/c,rear window defrost and park assist. But the problem is, with the jumper wire sitting in the relay socket, if I remove my key from the ignition, my blower motor continues to run, I can shut it off by turning the dial to "off" on the climate control but if I do forget, the blower motor will run till my battery is dead. I believe its because I am supplying constant power (using the jumper wire on the relay socket) and its no longer controlled by my ignition key. So what would cause the ignition power to stop flowing between the relay and fuse 42 ? whats between the relay and fuse 42? anything I am missing? oh and on the relay socket 3 of the 4 contact points have voltage across them, (not counting the middle contact point). the one that does not, I just run a jumper wire to it from any of the other 3 points then climate controls get power supplied to them and blower motors,a/c and rear defrost work and park assist. I replaced the relay with a new one and nothing happens, no power to fuse 42. Any help would be greatly apprechiated
 

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First of all, welcome to the forum!

I'm no good at electrical at all but all I can offer is to makes sure there are no taps in that fuse location. Beyond that, I'm totally lost.

Good luck!
 

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Discussion Starter #3
Fuse# 42 no power

no taps off that fuse location, just 2 factory wires going to the fuse socket #42. One runs to the blower motor power module( I think) and the other I believe comes from the ignition, But I am not sure. Anyone familiar with the wiring up to that "Run" relay and the fuse #42 on a automatic climate control 2007 Chrysler 300 C ?
 

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Discussion Starter #5
Thanks Bob

from earlier...
MADDOG said...
First of all, welcome to the forum!

Thank you MADDOG


Thank you Bob, for that wiring diagram. So if fuses 28 and 42 and 41 are good and the Relay-Run is good, then its safe to assume that Diode #2 is my problem ? Its why the Climate Control has no power ? Because from looking at that diagram its the only thing in between the Relay-Run and the Front Control Module. If testing with a ohm meter should I have any resistance accorss this diode, pulled out of the car?
and looking down the line, what is 13 C105 marked F923 20 PK/YL on that diagram ?
 

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Discussion Starter #6
Dont know if this is related but...

What is above the 3 fuses, 28,42,41 ? its says "S321" (In PDC) ? what is that ?
And I noticed there are 3 diodes in the rear trunk fuse box, 2 are smaller and one big one, what are they all for ?
 

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Here's a picture of the contacts on the relay. With the relay out and the key in the Run position you should have 12V at pins 30 and 86. You should have no voltage at pins 87 or 87A. You should have a ground or a very low voltage at pin 85. If you put your voltmeter + lead on pin 86 and the - lead on pin 85 you should get no voltage with the key off. With the key in Run you should get +12V. If all this is OK then the relay may be bad. Check the resistance between pin 86 and pin 85. It should be low as it's the coil of the relay. If the coil is OK maybe the contact is not switching. You could check the relay by taking it out and applying 12V to pin 86 and a ground at pin 85. It should click and you should get contact between pins 30 and 87. You may not be getting a ground at pin 85 by either a broken wire, diode failure or a defective Front Control Module. Good luck. Bob.
 

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Discussion Starter #8
voltage readings from relay-run with key in ignition and car running

So these are the voltage readings I am getting from the socket where the relay-run sat, with ignition key in on position.....

one lead on terminal 85 and the other to ground=14.3 v dc
one lead on terminal 30 and the other to ground=14.3 v dc
one lead on terminal 86 and the other to ground=14.3 v dc
one lead on terminal 87 and the other to ground= 0 v dc

one lead on terminal 86 and the other on terminal 30= 0 v dc
one lead on terminal 87 and the other on terminal 86=14.3 v dc
one lead on terminal 30 and the other on terminal 87=14.3 v dc

all these readings were taken when car was running with key in ignition
 

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Discussion Starter #9
almost forgot to mention

oh and forgot to mention...
with key in the ignition and car running...

with a dc volt meter...

on the relay-run socket

one lead on terminal 85 and the other on terminal 86= 0 v dc
 

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What is above the 3 fuses, 28,42,41 ? its says "S321" (In PDC) ? what is that ?
And I noticed there are 3 diodes in the rear trunk fuse box, 2 are smaller and one big one, what are they all for ?
I don't know what the S321 (In PDC) means.

I don't know what the three diodes are.

The 13 C105 is the designation of pin 13 in the C105 connector.

The F923 20 pk/yl is a 20 gauge wire pink/yellow in color coming from the Front Control Module in the Integrated Power Module. When the key is in the Run position it should be grounded to energize the relay. If there is no ground at pin 85 with the key in Run that's your problem as the relay is not being energized. Have someone turn the switch to Run then off and Run while you are listening and feeling the relay. You should hear and feel the relay energizing. If it does not energize then the problem is either a bad relay, a broken wire or a faulty module. Hopefully it is not a faulty module as it is costly. Good luck. Best regards, Bob.
 

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Discussion Starter #11
kinda starting to figure it out

So, after looking at few hundred web pages and many full vehicle, manufacturers electrical drawings. I figure S321 in pdc, just means there is a splice 321 in PDC which is the electrical distribution panel. So in simple terms, A splice having wire 3, 2 and 1 in the fuse box each leading to a fuse (28,41,42) which protects the circuit down the line by that fuse. I am trying to trace where the wire from Relay-Run, terminal 85 wire, leads to, I think it may be going to the Park Assist or further towards the front dash board. The wiring happens to run underneath the passenger seat. I did read many people complaining about water getting in there and causing electrical problems, such as rusting out connections. My problem may lay there or a loose wire harness or bad splice or at worst bad module.) But I do believe that the 3 diodes, 2 smaller ones and the bigger one in the rear fuse box, need to be replaced first. Diode #2 is the diode on the left bottom corner near the 10A small fuse. The other one closer to the outside is Diode #1, and the Bigger one, I'm not sure yet. From more reading into the diodes. I found that diode #2, had something to do with the a/c blower motor and rear defrost ( exactly, that's my problem, no ignition power to Blower motor resistor(called module in automatic climate control) because I don't have ground on terminal 85 from Relay Run)

I will let you know when I find something
Thank you for your help
 

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So these are the voltage readings I am getting from the socket where the relay-run sat, with ignition key in on position.....

one lead on terminal 85 and the other to ground=14.3 v dc
one lead on terminal 30 and the other to ground=14.3 v dc
one lead on terminal 86 and the other to ground=14.3 v dc
one lead on terminal 87 and the other to ground= 0 v dc

one lead on terminal 86 and the other on terminal 30= 0 v dc
one lead on terminal 87 and the other on terminal 86=14.3 v dc
one lead on terminal 30 and the other on terminal 87=14.3 v dc

all these readings were taken when car was running with key in ignition
If 85 to ground is 14V and 86 to ground is 14V then the relay will not pickup. There is voltage on both sides of the relay coil.

You said 30 to ground was 14V which is as it should be and 86 to 30 was 0 V which means they are connected.
When you jumpered the relay if you jumpered 30 to 87 which are the relay contacts and the blower ran that means that there had to be 14V at pin 30.

The whole problem is that the relay is not being powered with 14V on one side from the DC bus and 0 V on the other from the module as it should be.

The problem is either a broken wire, the diode, or a faulty module that is not supplying a low to energize the relay.

If you don't know how to check a a diode with a VOM then Google it and you will find out how to do it. Hopefully the diode is open as it is easier to replace the diode than to trace the wires or replace the module.

If it's the diode the price online is around $15 and around $25 at the dealer.

I hope this helps. Bob.
 

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We Need Help Please

I have been working with Less on his problem. We have traced the problem to the fact that the relay-run is not being energized. When pins 30 to 87 0f the relay are jumpered all works OK. With the relay installed and the anode side of diode no. 2 is jumpered to ground the relay engages. He has replaced diode no. 2 with a new diode. It still does not energize the relay with the key in the Run position.

I don't have a 2007 SM but am using a diagram for a 2006 model. It shows that the cathode side of diode no. 2 goes to C1 pin 20 of the Integrated Power Module and then to pin 22 of the Integrated Power Module. I have tried to see where the IPM gets it's run input with no success. Does anyone know where it gets it's input. The SM wiring diagrams are really hard to read for me.

Thanks, Bob.
 

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Discussion Starter #14
Problem fixed!!!!!!!!!

Thank you Bob, you are the best.
After you and I went over the electrical wiring diagrams,
We have determined that diode #2 in the trunk fuse box, the pink wire with yellow stripe was not turning relay run on.
After looking at numerous of Diagrams, We have determined that this pink wire with yellow stripe comes directly form the fuse box in the front engine compartment to C1 green wire harness that plugs into the bottom of the fuse box. While trying to get a voltage reading from the underside of that wire harness, while the car was running and the climate control dial turned on to allow the blower motor to run on full blast, I found that this pink wire with yellow stripe, came out of this harness quite easily, after taking a closer look, the end of this wire was completely corroded. Problem found!!!! I re stripped the end of that wire, pushed it back into Pin 21 of the Green wire harness C1 that plugs into the bottom of the front fuse box and the blower motor, park assist, all turned on.
Thank you very much Bob, I would not have found this problem with out all your help
 

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Discussion Starter #15
correction to last post

I re stripped the end of that wire, pushed it back into Pin 21 of the Green wire harness C1 that plugs into the bottom of the front fuse box

It was actually Pin 2o of the Green Wire Harness C1, and not 21
 

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Discussion Starter #16
Pictures of the 20 PK/YL wire

20 pk/yl is a 20 gauge wire pink/yellow in color coming from the Integrated Power Module(Under the Hood, the underside of the Front Fuse Box).

In the pictures you can see the pink/yellow wire that fell out of the green wire harness, Corrosion problem
 

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I seem to be facing the same problem with my 05 300c. I'm not getting power from relay to 30amp fuse #42.. I took the top off the fuse ran my test light with no power so I ended up jumping a wire from relay to fuse which works for now..
I'm trying to follow what you did with your issues based on the wires but I'm having a hard time following.. were is that wire located which cut off? Is it under fuse box? Did you do a video if so could I get the link?
I'm not 100% on following wiring diagrams but I'm not lost.. I could work around it but I need to know were to find the wire..
 
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