Electrical Diagnostics Question?

[slipknot1488]

Ok guys, I’m working on an electrical problem on my mom’s 2003 Mercury Sable wagon. Same as the Ford Taurus wagon. She has the electronic automatic temperature control unit. I need to make some fused jumper wires but I don’t know what size fuse I should be using. I have the wiring diagrams. I need to jump terminals on two sets of connectors on the remote climate control module. Any ideas what size fuse I should be using? Or a minimum at best? Any help would be appreciated. Let me know if you need more info.

Topic

[dave]

Your wiring diagram should already specify a fuse for that circuit.

-or-

Use one of these when your circuit is under it’s heaviest load then note the amperage. Then add like 5%. Round up to the nearest fuse and give it a try.

[slipknot1488]

It gets it’s power through the PCM and based on the wiring diagram the PCM is protected by a 15A fuse. Does that sound about right?

[dave]

could you post the wiring diagram with your proposed jumper?

[slipknot1488]

Sure, give me 10 mins. I’ll post a scanned copy of it.

[slipknot1488]

I need to troubleshoot the blend door actuator. I will need to move the jumpers to different pins. One set of jumpers would be from circuit 249 to 729 and second set would go fromm circuit 250 to 570. Actually after reading the diagram a little more closely I think the power comes from the central junction box but it’s still protected by a 15A fuse. Tell me what you think because I’m not 100% sure and I don’t feel like frying wires.

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[slipknot1488]

Let me re post them. They didn’t come out to clear.

[slipknot1488]

Let me know if you can see them well enough because they’re scanning clear but not uploading of the same quality I don’t think.

[slipknot1488]

This should be a little better.

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[slipknot1488]

And this is where I thought it got power from but I might be wrong.

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[slipknot1488]

I know I’m wrong because I’m using a jumper from circuit 729 which is a hot line.

[slipknot1488]

On one test I would be going from pin 21 to pin 11 and pin 22 to pin 8. I’m trying to troubleshoot the blend door actuator before I replace it. I’ve heard it’s a common problem but the issue I’m having with the heat is intermittent so I’m following the testing procedure in the service manual.

[dave]

On one test I would be going from pin 21 to pin 11 and pin 22 to pin 8.

This is a good idea. You could of course go pin 11 to 22 & 22 to 8 to get reverse polarity on the blend door actuator motor. Looks like you can get power from pins 10 or 11 if they are easy to get to, or just use external power if they are not easy to get to and just tie in directly to pins 21 & 22. Should be an easy and straight forward test.

Hope it doesn’t come down to this, but have fun tearing into that HVAC unit to get to that blend door actuator :unsure:

[slipknot1488]

Do I even need a fused jumper. The power feeds are already overload protected by those ten and 15 amp fuses, right? I’m already pretty sure it’s the blend door actuator and I have the radio out and some of the dashboard pulled away as it is. I’m in this one to fix it. I don’t hear it working when I change the temperature from hot to cold. It’s not like the car needs heat now but mom wants it fixed because we’ve been having funky weather here in NY and sometimes it’s cold enough in the morning and at night to warrant it.

[slipknot1488]

As long as I get the right pins I shouldn’t need a fused jumper, right?

[Herman Tyler Jr.]

Hello Wrench Turner & Slipnot 1488!

Pin 11, circuit 729, 20 gauge wire, red with a white tracer, hot at all times, 15amp circuit protection. This is the circuit that supply battery voltage to your “load” or (motor). Pin 10, circuit 298, 10amp circuit protection, is a switchable circuit to power up the control module. I personally would connect a jumper to a good known ground and volley that ground between pins 22 & 21, and use pin 11 to supply battery voltage to pins 22 & 21. If you are going to continue to work with electrical circuits “please take the time to learn how to read wire diagrams” you will save a lot time and money knowing how voltage is used in a circuit. BTW I’ll find and post a link from realfix realfast on youtube that has a course on how to read wire diagrams, this will add to the knowledge you have already. B)

[Author]

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