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Cruise Control
#1

The cruise control has started to cut out momentarily. It seems worse after a couple hours of operation. It feels as though there is an engine "miss" but it doesn't shut off. The "misses" seem to get more frequent. The cruise light will briefly glow brighter when it "misses" Last night there was a few times when the cruise would not set and the light would not come on at all. Then after a while it would set but continue "missing" occasionally.
I called Newell but they were unsure of what brand of cruise control they installed in my coach. I cannot find a wiring diagram or anything for it. I cant even find a fuse for it. I did replace the "set" relay but got no satisfaction. Any ideas would be appreciated!!

1993 Newell (316) 45' 8V92,towing an Imperial open trailer or RnR custom built enclosed trailer. FMCA#232958 '67 Airstream Overlander 27' '67GTO,'76TransAm,'52Chevy panel, 2000 Corvette "Lingenfelter"modified, '23 Grand Cherokee.
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#2

If you have the same cruise control as I do, I would first adjust the sending unit. There are two sending units on a flywheel like disk with large holes drilled around the outside edge on the driveshaft. One sensor is located on the bottom and one on the top. They should be set to the thickness of a credit card (0.030 inches). Using feeler gauges is a bit tricky because the sensors are magnetic and the gauge will 'stick' to the sender unit.

First check the bolts that hold the disk to the flywheel. Mine were loose and allowing the disk to flex. If you have a VMSpc unit and you see irregularity in the cruise control speed setting, it likely is the sensor either failing or out of adjustment or the disk plate flexing due to loose bolts. As I recall, the speedometer sensor is white with blue or green stripes and the odometer is yellow with blue or green stripes. I believe the speedometer sensor is an ISPro R-8932 and the cruise control sensor is likely the same.

Michael Day
1992 Newell 43.5' #281
NewellOwner.com
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#3

Michael is spot on about the sensor.  It will cause the cruise to drop out if not set correctly.  The cruise is part of the DDEC and receives a frequency signal from the sensor.  The sensor is called a MAG PICKUP and most any will work.  The closer the tip is to the toothed wheel the stronger the signal.  In generators, the accepted method is to let the tip touch the tooth (directly on top of the tooth) and back out one half turn.  That may be .030" , I've never measured it since it is inside the flywheel housing.

Gordon Jones
2000-45'-2slide-#567
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#4

on my 90, the cruise would cut out. after adjusting the sensor that michael is referring to, it fixed it.

tom

2002 45'8" Newell Coach 608  Series 60 DDEC4/Allison World 6 Speed HD4000MH

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#5

I got under the Newell yesterday . Both sensors are tight and adjusted properly. My next step is to replace the cruise sensor. One wire is white with green stripe, the other is yellow with green stripe. Michael suggested the isspro sensor,, they appear to be identical to the sensor Michael suggested. I'm still unclear which is speedometer and which is cruise control. I will call Newell again on Monday.

1993 Newell (316) 45' 8V92,towing an Imperial open trailer or RnR custom built enclosed trailer. FMCA#232958 '67 Airstream Overlander 27' '67GTO,'76TransAm,'52Chevy panel, 2000 Corvette "Lingenfelter"modified, '23 Grand Cherokee.
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#6

For what it's worth, I had the same problem on my 89.  Didn't know which pickup did what.  Unhooked one and drove about 1/4 mile.  that told me which pickup was speedometer.  After determining which was for DDEC, I ran a two conductor cable from the MPU to the drivers station.  Luckily I was able to run the wire inside up through the floor near the engine compartment by following another cable's protrusion.

The cable was connected to the MPU (without the DDEC) and I measured the voltage and frequency on a multimeter while driving.  The voltage needs to be about 2 to 5 volts (it will be an AC signal) and you should see frequency vary in direct proportion to the speed.  If that reading is correct, look for a bad connection at the DDEC input.  That is where I found my problem, corrosion in the weatherpack DDEC connector.

Hope this helps a bit.

Gordon Jones
2000-45'-2slide-#567
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#7

Ok to sum up what I have done so far:
replaced cruise control relay on under dash panel in front of passenger.
Installed new Mag sensor . Hooked it to yellow wires w/ green stripe per Chuck at Newell. He thought the white/green were for speedometer.
Adjusted per specs (.030")
Replaced both toggle switches (Cruise on and the set/resume momentary switch)
I pulled all three weather pak fittings on DDEC computer and could not see any corrosion. Each of these plugs contained 2 or 3 wires. I am understanding these are the external inputs/outputs for the DDEC. There is a larger plug which looks to contain 30 pins which I am assuming are the DDEC internal sensors etc that would not apply to my problem. I did not pull that because I do not want to introduce more problems to the scenario unless I find that it could provide a solution for sure. It appears that I will have to remove some brackets etc to access that plug.
I talked to Chuck at Newell. He had no more ideas to offer. I asked about a wire schematic. He said they don't do them since each coach is custom and therefore different. He said they try to use the same color of wires for common items. So I'm stumped!!!
Still when I try to set the cruise I get no green light and no cruise set.
So if I understand this right the components are:
cruise on/off switch
cruise set/resume switch
1 relay
1 magnetic speed pickup
the DDEC computer.

When I start the engine and it is going through its start checks the green "set" light comes on momentarily as it always has.



Is it possible to wire the magnetic pick up backwards?
Are there other components I am missing?

1993 Newell (316) 45' 8V92,towing an Imperial open trailer or RnR custom built enclosed trailer. FMCA#232958 '67 Airstream Overlander 27' '67GTO,'76TransAm,'52Chevy panel, 2000 Corvette "Lingenfelter"modified, '23 Grand Cherokee.
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#8

It's been a long time since delving into this problem but I'm pretty sure the MPU enters the DDEC in the 30 pin connector.  It's worth a check to see if there is something wrong.  Check the wires going into the connector and the pins on the DDEC side.  

I've dug up the drawings of your DDEC -II 30 pin plug.  The first page of the pdf is the diagnostic connector inside.  You can check codes by watching the "check engine light" CEL while shorting pins A to M.  Use this for future diagnostics.

 Wires 556 & 557 are from the MPU to the DDEC (see page 2),   Page 3 shows the wire colors to be 556 BLUE LT/BLK & 557 BLUE LT/ORN and are in positions E2 & E3.  Page 4 shows the 30 pin ECM connector.  

Now do a continuity check of those wires from the 30 pin to the MPU (while unplugged) to be sure there is a path.  The MPU output is AC so polarity is not a factor. 

If you have a good MPU and the wires are continuous and the pins are not corroded or bent or pushed back in the 30 pin, the ECM should be getting a road speed signal.  You've changed everything else so it should work unless there is a wiring problem from the switches to the ECM.  But, you have a drawing now so hopefully it will be an easy fix.

[attachment=4077]

Gordon Jones
2000-45'-2slide-#567
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#9

Thank you Gordon!! I will dig into this!!!

1993 Newell (316) 45' 8V92,towing an Imperial open trailer or RnR custom built enclosed trailer. FMCA#232958 '67 Airstream Overlander 27' '67GTO,'76TransAm,'52Chevy panel, 2000 Corvette "Lingenfelter"modified, '23 Grand Cherokee.
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#10

In addition to what Gordon said, while the 30 conductor plug is pulled, checking the voltage on the pin that sets the cruise control to the "on" setting. Since you first reported the problem getting worse while driving it may be worthwhile to leave it on for a while and continue to check the voltage. I would also shake the wiring near the MPU and the ECU while checking that voltage. If indeed the problem gets worse as you drive I would suspect heat as contributing to the problem, the the failures are entirely random while driving then I would suspect vibration as the instigator. The part subject to the most change due to heat would be near the ECU rather than the MPU.

The thing I find most puzzling is your statement that the cruise light got brighter momentarily when the cruise burped. That would indicate a momentary increase in voltage to the light. I doubt the internal relay in the ECU would alter its behavior at this moment so the internal supply voltage to the relay must change at that moment, which leads me to wonder if the electrical supply to the ECU is somehow compromised, or, heaven forbid, the ECU itself has an internal problem.

Jon Kabbe
1993 coach 337 with Civic towed
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