Day 5 of this cruise control saga.
After being somewhat of a loss as to what is going on, I was rummaging around the interwebs looking for more ideas. I ran across this test that I have actually seen a Youtube video of the same, but this has a more detailed explanation.
The formatting is screwed up so I added a screen capture. The link is from Dave70 at the F150 website (I think??).
I have attached a schematic from a 1998 Explorer (or thereabouts); this schematic is clearer to understand the interface to the Speed Servo Control module. You can see the Orange/Lt Blue wire on Pin 1. I added a Green/White wire to my original E-350 SCS.
The difficulty for me with the 1997 E-350 is that there is no speed control indicator lamp in the dash and there is no pin out for Pin 1 in the Speed Control Servo (SCS). This diagnostic test is very very useful and so it is worth adding a wire to get to this signal. It is actually a ground signal which means if you have an indicator lamp (such as an LED) connect the other end of the LED to a +12V switched source and then connect the low side to this Pin 1 on the SSC. The SCS pulls Pin 1 to the ground when it wants to light the LED.
One warning is that this picture shows too much wire on the connector and the mating connector can not be pushed on. I guess I can drill, out the mating pin as there should be no contact there just interference from the plastic. (minor details)
I'm going to add one of these to my dash as the diagnostic test is much better than the FSM diagnostics.
So the results from both my original SCS and the $15 2020 Explorer SCS from the junkyard is the same. I seem to pass all of the button tests but fail the overall static test (first part of the test). Recall this is no surprise because I have ohmed out the switches through the clock spring and confirmed that the switches were fully functional . I measured the 2.2K, 680, and 120 ohm resistances specified (on page 31-1) of the factory Electrical and Vacuum Troubleshooting Manual.
The result is that I get either 2 or 3 blinking lights at the end of the test which
- 2 flashes - BPP defective, circuit is defective, brake applied, CPP switch or jumper (if equipped).
- 3 flashes - deactivator switch is open or circuit defective.
Regardless of which it is it seems to indicate bad connections in the harness or switches. I have checked the switches and actually replaced all of my LED signal/brake lights (in the rear) with the original incandescent lights.
So at this point there is nothing wrong with my switches, nothing apparently wrong with either SCS and i have tested bot the brake switches and diagnosed the high floating voltage (on pin 4) due to LEDs.
I'm pretty much left with only one alternative which is to replace the clock Spring. Unlike the SCS , the clock spring is a wear item similar to the switches. It makes a sound but not really a noise of clicking as I have seen in You tube videos.
Both SCSs think i have connection problems so I found a NOS, Factory, model specific clock spring on eBay.
1997 - 2003 Ford E-150 E-250 E-350 E-450 Air Bag Clock Spring Contact new OEM
I also found a relatively inexpensive replacement set of switches that should have the led lights in them. As I previously mentioned the 1997 clock spring originally installed is wired to power the LED's in a set of switches if present. This was not necessary but since I'm there it would be nice to have the Cruise control lighted button on the steering wheel.
1997-2004 FORD EXPEDITION F-150 F-250 F-350 CRUISE CONTROL SWITCH SET OEM 98 99
As mentioned earlier I already bought yet another SCS from an E-150 with 45K miles.
Chassis ECM Cruise Control Servo Assembly Fits 92-94 98-99 FORD E350 VAN 3303566
Changing the clock spring involves pulling the seeing wheel and steering lock, so I figure I will also do something about my disintegrating shift boot around the transmission gear selector. Excluding the $20 in junkyard parts, I'm not into this for $200 but with good to new factory parts (excluding the Dorman boot).
Auto/Manual Trans Shift Boot Fits Ford Expedition 47996 Dorman - HELP
I will reiterate that the electronic control board that is on top of the SCS is a high-quality sealed surface mount device. It should last for a long time. There is little to causing something like this to fail short of an electrical event in the charging system. From what I have seen the most likely failure mode is you the cable comes loose or there is water intrusion into the gear/motor portion of the SCS and it seizes. There is a larger protrusion one the 2020 SCS compared to the 1997 and I will compare this to the low mileage SCS I get in a week or so. I suspect that that other than mounting plates which can be swapped the gear motors are interchangeable (it interfaces to the throttle with a cable which should be virtually identical for many vehicles).
Any vehicle with these same set of steering wheel switches will have to have identical functionality (because of the specific resister values in the switches) and so the SCS's are all probably interchangeable. It is possible this extends beyond these switches, but I would not hazard a guess as to whether this is really true.
The set of switches I bought linked above quotes 1997-2004 for Ford Expedition so any SCS up to 2004 is a safe bet to be interchangeable.
I think I have done all I can do for now till the new parts come in.
I'm going to get back to the van build and finish installing my roof-mounted solar water heater
Originally Posted by*Dave70* **
I was hoping that hatch_1989 might be able to post the rest of the diagnostic procedure that is posted earlier in this thread. If not, is there somewhere that I can find it? Thanks.
I have used this built-in self diagnostic test on my 2003 Econoline with good success:*cruise*control*self test*
Enter self-test diagnostics by depressing the speed*control*OFF switch while turning the ignition key ON, making sure the engine does not start and is not running. The speed*control*indicator on the instrument panelwill flash once to indicate that speed*control*module entered the*diagnostic*mode. Five additional flashes at this point indicate a defective speed*control*servo. Release the OFF switch.Press the remaining switches in this sequence: ON, RESUME, COAST and SET/ACCEL.If the ON switch is not depressed within five seconds after entering the diagnostics mode, the module times out and the procedure must be started over.The speed*control*indicator lamp will flash as each switch is depressed. Press each switch in the sequence immediately after the indicator light goes out for the previous switch.NOTE: There will be a slight delay when the last button is pressed and the lamp flashes.A lamp flash with the last button (SET/ACCEL) indicates that the static*test*passed. If the lamp does not flash with the last button and there are no additional flashes of the lamp, the switch is defective.If the lamp does not flash with the last button, and additional flashes occur, follow the chart below for trouble codes:2 flashes - BPP defective, circuit is defective, brake applied, CPP switch or jumper (if equipped).3 flashes - deactivator switch is open or circuit defective.4 flashes - vehicle speed signal is out of range or circuit is defectiveImmediately (.25 second delay) after the static*test, the speed*control*servo does a dynamic*test*by automatically actuating the throttle lever from 8 mm (0.315 in) to 12 mm (0.472 in) of travel from the idle position. During the dynamic throttle pull, observe throttle movement to witness any binding or sticking of the speed*control*cable and correct connection of speed*control*cable to throttle lever. Make sure the throttle returns to the idle position