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Old 04-16-2021, 10:02 PM   #1
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1997 E-350 RB 5.4L 125K miles Cruise Control Stopped Working

As described in the title the Cruise Control quit in the E-350. I have been working on this for the last 3 days with no luck. I will not go through all the gory details of what I have done but with sourcing used parts at the junk yard to try and diagnose the issues.

First some background: I bought the van new in Nov 1997 (Ca vehicle). The van DID NOT come with CC but I had the dealer add the CC before I picked it up NEW.

From what I can tell (I have Ford factory service manuals (two binders) and the Electrical and Vacuum Troubleshooting manuals for 1997) the only difference between this and a true "factory" install is that the dealer did not change out the brake master cylinder to include the brake pressure switch, but instead just wired those inputs in parallel to the brake switch under the dash. It is not redundant but it has never failed until just recently.

Today I have verified almost all of the signals to the Servo Control Unit (through the clock spring) that come from the steering wheel (on, off, Resume, set, and coast) as well as the brake input for BOO and Pressure switches (brake switches used both ohms and volts). I did the steering switches using an ohmmeter (and will double-check the measurements tomorrow using voltage). I was concerned about the clock spring so I measured right at the Servo Controller plug except for the Dark Blue (DB) which is +12V from the fuse box.

I have also tried to diagnose using the flowcharts in the FSM, but honestly, they do not make much sense and I do pass most of it if you guess correctly what the test conditions are. I'm an electrical engineer so there is less uncertainly but just testing according to the schematics and confirming the as-built harness. There are various discrepancies I found between the FSM and the Electrical troubleshooting schematics.

Finally, I will mention I did procure a junkyard Servo controller from a 2000 Explorer for $15. I swapped the servo electronics module onto my servo controller and tested that as well. I'm not sure if this should or should not work. The form factor is the same and the surface mount design is very similar although there was an obvious layout change. This is a potted surface mount design that should be very robust and it is hard to imagine it ever failing with its limited service life.

To this point I have had no luck; nothing I do gets the CC to engage. I'm now down to the VSS input that comes from the transmission. The Speedometer works beautifully (see attached pic ; note odometer on a trip from Tucson to Phoenix). Based on the schematics, apparently, the VSS signal goes to the Dash, PCM, and Servo controller in parallel so there are no cascade failure possibilities.

I'm contemplating buying this tomorrow is there is any suggestion the Servo Amp is bad, but there is a lingering doubt that for some reason it will not fit my 1997 ???

Does anybody know why this doesn't work? or can't work?

Chassis ECM Cruise Control Servo Assembly Fits 92-94 98-99 FORD E350 VAN 3303566

https://www.ebay.com/itm/Chassis-ECM...6/363202032186

My Servo Controller looks beautiful inside (zero water intrusion) despite being basically dry of lubrication. I did put a small dab of waterproof bicycle grease on those gears just in case it does still work. I have also been cleaning connectors and adding dielectric grease as I go along.

One final thing is that I did verify that the power and ground for illumination are already in the clock spring I have and in fact the junkyard broken switches I bought for $5 do illuminate.

Any help suggestions would be welcome before I embark on Day 4 of this ordeal tomorrow...............

Especially if there is anything specific to this 1997 year model that I should be aware of. I am in the middle of a van build and suspension upgrades but this CC is bugging me.
Attached Thumbnails
IMG_3080_123456.jpg   1997_E-350_RB_5_4L.jpg  
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Old 04-17-2021, 12:28 PM   #2
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OK I have some more info:

I blocked up the rear axle so I could run the rear wheels in drive.

I also figured out that the 97 E-350 does not have an indicator and so does not use Pin 1 on the Servo Amplifier (an apparent output to the display)

Despite there seeming to be a great number of different wire colors on the Explorers, this indicator output seems to be the only real functional difference.

A.) My VSS signal is present at Pin3 (as should) (all pin reference the Servo Control 10 pin connector)

B.) The Brake Pressure Input at Pin 9 is:
At Rest 0 Volts
Brakes Applied 14.3 Volts (engine running)

C.) The Brake ON/OFF switch is:
At rest 5.5V
Brakes Applied 14.3 Volts


These last voltages seem strange like something is pulling up the BOO switch voltage. I did change all lights to LED including the High mount third brake light. I think this might be my problem.

As a test i might just disconnect that switch.....................
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Old 04-17-2021, 03:14 PM   #3
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Another update. The high floating zero voltage was a result of the LED taillights (specifically the brake lights). When I put the original incandescent lamps back in that pulled the voltage down to less than 1 volt (the resistance is less than 0.5 ohms). When I used a 140 ohm pull down the voltage got below 1 volt as well.

As best I can tell all the correct voltages are applied to the servo controller now and it still doesn't work including the 2002 Explorer one from the junkyard.

I ordered the eBay one mentioned above. it will take over a week to get here so I will do one last test drive to see if there is some logic detecting that the van in on blocks. It almost seems like it wants to hold speed but then it kicks off.
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Old 04-18-2021, 01:05 PM   #4
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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

https://www.ebay.com/itm/1997-2003-Ford-E-150-E-250-E-350-E-450-Air-Bag-Clock-Spring-Contact-new-OEM/264187210444

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

https://www.ebay.com/itm/1997-2004-FORD-EXPEDITION-F-150-F-250-F-350-CRUISE-CONTROL-SWITCH-SET-OEM-98-99/293725319010

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

https://www.ebay.com/itm/Chassis-ECM-Cruise-Control-Servo-Assembly-Fits-92-94-98-99-FORD-E350-VAN-3303566/363202032186

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

https://www.ebay.com/itm/Auto-Manual-Trans-Shift-Boot-Fits-Ford-Expedition-47996-Dorman-HELP/392665281240

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 .
Quote:
Quote:
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 panel will 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 defective Immediately (.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
Attached Thumbnails
ExplorerSpeedServoPinout.png   SpeedServoPin1_INDICATOR Control_Mod for 1997.jpg   SpeedControlDiagnosticTest.png  
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Old 04-18-2021, 01:35 PM   #5
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I'm going to clarify something that I misunderstood before.

So when I bought the van, it did not have Crusie Control from the factory so I had the dealer add that before I picked up the van. I was under the impression that they simply hard wired the pressure switch to the Brake ON/OFF switch (BOO) thereby being functional but at reduced reliability (no second brake signal to confirm the cruise control should remain active)
Changing the brake master cylinder pressure switch is not something they do as part of this dealer upgrade and my van does not have a pressure switch at the master cylinder.
.
What I now know is that that the BOO switch is under the dash at the end of the rod that pushes on the brake master cylinder, and the dealer added a surrogate for the master cylinder pressure switch is under the dash. This redundant electrical switch has a flexy metal arm that goes against the brake pedal arm and actuates the switch. So it is still redundant, just not using pressure.

Here is one of the complexities that I do not have a definitive answer for. The BOO switch is normally open, and closes when brakes are depressed. This is the switch that provides the power (high side control) to the brake lights.

With incandescent lamps (resistance less than 1 ohms) any voltage at the open BOO switch will be actively pulled down by the lamps. However, when you put in LED lamps (I have 4157/3457 Amber, 3157/3156,3057 Red, 3157 White . These projector types are very bright) the resistance is much higher and so whatever is trying to push up the voltage at the open BOO switch has an easier time of it. I have measured 5.5V with the LEDs installed. 140 ohms is enough it pull it back down to under 1 volt.

I don't know if this is affecting the SCS operation because the FSM uses a 10V threshold to determine the active brake condition. So even 5.5V is well below this. However, it does explain a mystery that I noticed that with the brakes off, the rear tail lights seemed to have a dim glow. At night this would be overshadowed by the tail lights and during the day it is not noticeable due to the sunlight.

I still do not know for sure whether this 5.5V brake inactive signal is a problem, I installed all of these LEDs in February 2020 and I really do not know if I have used my cruise control in the intervening time. I don't drive the van much and mostly in the north Tucson area where I avoid the freeway if possible.

The point here is that I have switched over almost all of my light on the van to LED because the incandescent light is generally all powered directly from switches that tend to overheat and melt wires (including the dome lights).
This brake light thing was a mystery that I now know can be solved by installing a small resistor at the output of the BOO to the ground. You could also do it at the lamp as well.

YITAMOTOR 3157 3156 3057 - Rear Brake LED Bulb for Caravan Trailer, 3057 3047 (2 Pack), Red

https://www.amazon.com/-/es/gp/produ...?ie=UTF8&psc=1

I also installed one of these on the High mount rear brake. Flashing tail light is legal in CA and AZ and I think most states, but there is a precise timing pattern in the number of pulses you can have. These are close but technically not within the spec for CA.

I don't know if this is causing any problem, so I have removed it for now till I get all of the cruise control stuff sorted using simple incandescent bulbs.

I expect I will be able to reinstall it all using the 140 ohm pull-down and all will be good after the Crusie control is operable. I'll update on that later.

2X GS-100A Flash Strobe Controller Box Flasher Module LED Brake Tail Stop Light

https://www.ebay.com/itm/2X-GS-100A-Flash-Strobe-Controller-Box-Flasher-Module-LED-Brake-Tail-Stop-Light/303682736487

Quote:
Originally Posted by posplayr View Post

B.) The Brake Pressure Input at Pin 9 is:
At Rest 0 Volts
Brakes Applied 14.3 Volts (engine running)

C.) The Brake ON/OFF switch is:
At rest 5.5V
Brakes Applied 14.3 Volts


These last voltages seem strange like something is pulling up the BOO switch voltage. I did change all lights to LED including the High mount third brake light. I think this might be my problem.

As a test i might just disconnect that switch.....................
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Old 04-21-2021, 08:38 AM   #6
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This is an exceptionally lengthy and detailed post unfortunately I get lost in all the facts etc---my bad, nothing wrong with your writing.

I might be able to shed some light on this for you but that would pretty much necessitate a phone call if you're up for that? I'll PM my contact info---you're welcome to call, time of day sometimes catch as catch can BUT all calls are returned ASAP.

HTH
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