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Had been running good for the past couple of weeks. Out of nowhere, I noticed I had no directionals. Did some research found the run circuit fuse had blown. Replaced it, things seemed ok, had directionals, overhead display worked again. Went to do some errands, noticed no directionals again. Replaced the fuse at my next stop. Checked directionals all working. Great. backed out of my spot, no directionals. So no issues until I put it in reverse. Checked wires in back, fine. Disconnected the TRS, and the connections that feed the rear of the truck. Put it in reverse, fuse is fine. reconnect the TRS fuse pops. Tried tracing it back with no luck. TRS is a year old but not ford.
Is it possible the TRS is shorting out internally? The harness is still in factory spots, and looks undisturbed. Electrical is not my strong suit, so I need some suggestions.
Don't think the DTR switch is the fault. While in reverse, 0 ohms on pins #11 (power to reverse lights) and #9 (feed power) which makes sense to me, nothing between #11 and anything else. Need to check wire #11 Black/pink.
I separated the wire connectors just after the transfer case. Fuse is fine in reverse until I reconnect the plug on the DTR.
While in reverse, 0 ohms on pins #11 (power to reverse lights) and #9 (feed power) which makes sense to me, nothing between #11 and anything else. Need to check wire #11 Black/pink.
You cannot assume it's good until you've checked for any short to ground of either of those pins on the DTR switch itself. No indication you did so.
If the above check passes (no short to ground in the switch), then you need to check for a short to ground on the output wire of the switch (BK/PK). Be sure you use the lowest range on your meter, a "good" circuit will only measure a few ohms. A shorted to ground circuit would measure zero (or very close).
You cannot assume it's good until you've checked for any short to ground of either of those pins on the DTR switch itself. No indication you did so.
If the above check passes (no short to ground in the switch), then you need to check for a short to ground on the output wire of the switch (BK/PK). Be sure you use the lowest range on your meter, a "good" circuit will only measure a few ohms. A shorted to ground circuit would measure zero (or very close).
Will check both #11 9 for short to ground.
Have been working on checking BK/PK, but the harness towards the rear has no BLK/PK wire. 1 pin has 0 ohms, and 4 or 5 have low .006 ohms, from the BLK/PK wire at the DTR to the rear of that section of wiring harness.
Appreciate the help!
Last edited by samsdad02; Sep 19, 2022 at 01:07 PM.
Reason: clarifying
Realized the wiring diagram I found online was for 2002. I assUmed they are the same for 2003. The DTR plug says position 1,7 and 8 aren't used. Position 1 is not used,but 7&8 are. position 7 is also BLK/PK and ohms out when I connect my meter from #11 to #7, both BLK/PK. They also both ohm out when connected to ground. I'm guessing they are not supposed to be connected to ground. Also assUming #7 is for the auto dim mirror.
I don't know what you mean by "ohm out'. Post the meter's actual readings, including units, along with the two test points between which the measurement was made, as that is unambiguous.
FWIW, with the DTR switch's connector disconnected, every pin on the switch should read an open circuit to chassis ground. If any show zero (or very low) resistance readings, the switch has failed internally (shorted).
The reversing lamp circuits and the DTR switch on the 02 and 03 Excursions are the same, also the same as the SD pickups.
I don't know what you mean by "ohm out'. Post the meter's actual readings, including units, along with the two test points between which the measurement was made, as that is unambiguous.
FWIW, with the DTR switch's connector disconnected, every pin on the switch should read an open circuit to chassis ground. If any show zero (or very low) resistance readings, the switch has failed internally (shorted).
The reversing lamp circuits and the DTR switch on the 02 and 03 Excursions are the same, also the same as the SD pickups.
What I mean by ohm out is zero resistance 0.0 on my meter. Fluke auto ranging multi meter. All of the pins on the DTR are open to ground. The 2 BK/PK wires (#7 & 11) on the plug for the DTR have 0.0 ohm to ground and each other with #27 fuse removed.
Pin 11 of the harness is the only one we're interested in regarding F27 blowing when the shift lever is placed in REVERSE. Pin 7 should be VT/YE, not BK/PK.
That BK wire goes to: A splice that feeds the interior rearview mirror and a feed into the in-cabin fusebox (CJB). In the CJB, it splits and powers the trailer reversing lamp relay and to an output that goes to the parking aid module (PAM, behind RF kick panel) and the two reversing lamps at the back of the truck.
If you have one, use a short-circuit detector.
If your meter has a continuity beeper, turn it on and connect the meter between that BK/PK meter and ground. The meter should be beeping. Start disconnecting potentially shorted components and branch circuits and see if you can either identify tthe specific component or, at least, a segment of the harness where the short circuit is at. I would start by pulling both rear lamp assemblies and remove the reverse lamps, checking for broken filaments or other obvious faults.
There is a plug on the frame rail that connects the main wire bundle front to back. I have unplugged that.
My Fluke meter has a constant tone (.0000 ohms) when I connect pin 11 to ground, in park no fuse in #27.
I just picked up a circuit checker. It has tone (no short) from the CJB, once I get under the hood the tone gets softer the further the sensor moves away. Along the frame rail, it stops making tone until I get to the DTR plug, then its faint. The directions with it suck, there is almost nothing online on how to use it.
I'll go thru it again tomorrow, wife's birthday takes priority.
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