Electrical 02 GT - Multiple Electrical Issues

[MattMan02GT]

Hey everyone, as I said in my introduction thread I picked up a 5 speed 2002 GT about a month ago. Of course after I bought it I started noticing a couple electrical issues.

When I have the headlights on and engage the high beams they come on right away, but the indicator on the dash does not come right on. It might take a minute or two to come on. The traction control button appears to work as it should and the orange light will come on when disabled, but should the green "burnout" emblem also light up on the dash at this time?

When I have the blower set to bow out of the vents it typically does it, but occasionally it appears to be stuck blowing out the defrosters. The really wonky part though is often if I'm going up a hill, around a corner, or romping on it, the car will switch from vents to defrosters then back to vents whenever it wants to?

Any insight would be greatly appreciated! Thank you in advance

 

[wmburns]

Here's some information on the cluster that may be of help.

Cluster PC foil trace repair.
https://www.allfordmustangs.com/forums/v6-tech/304608-my-odometer-goes-off.html#2657361

It's my understanding that the traction control green light will only come on when traction control is actually reducing power and applying the brake. IE doing it's job.

The vent dampers are driven via engine vacuum. The default position is "defrost". IF the engine vacuum goes away it would be expected for the air to default back to defrost. What could make this happen?

• Leaking check valve to the vacuum reservoir
• Leaking vacuum line between the engine through the firewall to the vacuum reservoir.
• not enough engine vacuum.
• Leaking damper motors
• Leaking AC mode control switch.

When you understand that the damper motors are driven by engine vacuum it's easy to understand why driving conditions of low vacuum may affect the damper motors. Note, that in a normally working system would maintain vacuum and the check valve would prevent the vacuum from bleeding off.

 

[MattMan02GT]

Hey wmburns, thank you for your input! My car does have an aftermarket radio in it actually, do you think they could have messed up that ground and that would just cause an intermittent issue with only the high beam indicator light? Or do you think it could be a bad solder joint? Because (so far!) the odometer has been fine and all other lights appear to work. Especially the check engine light for the EVAP leak for that leaky fuel filler grommet I'm hoping to replace tomorrow night if the rain holds LOL.

Regarding the vacuum and defroster issue, now knowing it's vacuum operated that makes perfect sense. So I'm losing vacuum at some point, likely. Do you happen to have a diagram showing the location of the vacuum line and check valve leading to the unit? Previously I rebuilt my 05 F150's 4wd system and that one being vacuum operated as well I learned those check valves can be a pain! Some WD40 and an air duster applied gently did the trick though and the check valves have been working since (knock on wood). I hear a hissing sound when I'm gently accelerating up a hill that I assumed was the cold air intake....but I already had to replace 2 cracked boots on the CAI that were letting in unmetered air, but apparently not enough to throw a code. I'm wondering if that hiss is related to my defroster issue.

 

[MattMan02GT]

Does anyone know if the SN95's have the same vacuum layout as the foxes? I've only been able to find a fox diagram so far in my searching. Thanks!

 

[Neuron]

Is this what you are looking for?

 

[MattMan02GT]

I'm actually not sure! LOL. I will have to look under the hood tonight once it cools off a little bit outside. I don't know if that line shown going "to chassis" is the start of the run I need to look at? I imagine there is a Tee against the firewall or something and one of lines feeds the blower door?

 

[Neuron]

My garage is a mess(thanks son)but if needed I could probably find my Ford Shop Manual Supplement with the vacuum schematics if that one doesn't do it for you.

 

[MattMan02GT]

Neuron, I did a little more digging on lunch and found the attached diagram at http://diagrams.hissind.com

That site is ad laden, but claims this is the diagram for 94-98 mustangs. As long as they didn't change anything going to the 99-04 this should work. There is the same yellow hose going to the defrost motor that the fox cars had as well, so fingers crossed lol

 

[Neuron]

Great site(bookmarked), looks like it should match up, don't mind digging out the manual if you need.

 

[MattMan02GT]

It might be a night or two until I can work on it, but I'll let you know how it goes. And thank you on the manual!