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go-west.., Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 1185
Experience:  Technican with 20 years experience focused on engines and electrical.
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Have a 2000 Sterling Prime Mover with a Cat C12 motor. Have

Customer Question

Have a 2000 Sterling Prime Mover with a Cat C12 motor.
Have engine warning light coming on at 1500-1600 rpm and unable to rev engine beyon this while driving. In neutral and reverse angine will rev above this and with no engine light.
Code reader reads the code when light on as
PID84 Vehicle Speed
FMI1 Data valid but below operational range
I have replaced the speed sensor on the output shaft, which has made no difference.
Submitted: 9 months ago.
Category: Medium and Heavy Trucks
Expert:  go-west.. replied 9 months ago.
Good evening
Yes your are on the right track
The vss is a good start
The pid 1 means vss lost of signalI'll need your engine serial number and do you have a auto or manual trans.. thanks
Customer: replied 9 months ago.
Manual Transmisson
ENG # 2KS59576
Expert:  go-west.. replied 9 months ago.
Please go to your ecm
There is 2 connectors there,
Are they 40 Pin or 70 Pin?
Customer: replied 9 months ago.
Hard to see
The one towards the front of the motor is 70
The rear one looks the same also
Expert:  go-west.. replied 9 months ago.
the plug towards the rear is the one you want. Pins 32 and 33 go to the vssBut before you ohm out the wires take the vss out and make sure the tone wheel that the vss reads off is tight. Gently with a flat head screw driver try to move the tone wheel. If loose, tighten the yoke nut. It tight then ohm out the wires. Good luck and let me know how you do.
Customer: replied 9 months ago.
Checked the tone wheel, and seems tight. No play at all.Am I checking the Ohms from the Sensor to the ECM?While looking at the sensor wire, it is apparent that half of it has been ripped off. With a section of the two wires replaced with a new section of different wires to the sensor. There is a join, and the wires change from Black & Green Twisted, to Red & Black.Could the wires be around the wrong way - Ie + & -?
Are we able to get a new loom section and replace from the ECM to the Sensor?
Could we use standard signal wire so that their is no join?
Expert:  go-west.. replied 9 months ago.
You can use any wire but it has to be twisted
Customer: replied 9 months ago.
Thanks.Rejoined the wires and twisted them. But he made no difference.Assuming that polarity makes no difference.Have now lost all instruments. No speed, no revs, no voltage etc. but truck still runs fine and Engine warning light comes up at 1500 still and derates.This point to a thing specific?
Expert:  go-west.. replied 9 months ago.
Go you please take a picture of you dash please I want to see what style you have.
Customer: replied 9 months ago.
Disconnected battery I've weekend and instruments are now working.Back to the sped sensor. What am I checking ohms across?
Expert:  go-west.. replied 9 months ago.


accross 32 and 33 i would like to see 800 to 1200

let me know what you get.

Customer: replied 8 months ago.
Finally got to checking the ohmsAcross 32 & 33 at the ECM25.95 K ohmsSo what is this telling us know??Have also discovered the the two wires from the speed sensor go back in to the cab. Assume to the speedo.Cheers
Expert:  go-west.. replied 8 months ago.

Hey, there he is !

is there 4 wires or 2 coming from the VSS?

if there are 4 wires with 2 connectors please please tell me the resistance of the other connector,if there is one.

Customer: replied 8 months ago.
Two wires from the vss.Inch coed the resistance at the ECM across pins 32&33
Customer: replied 8 months ago.
I checked the resistance......
Expert:  go-west.. replied 8 months ago.
The resistance seems high but the vss is new. All that remains is to make sure that the yoke nut is tight as the pick up wheel for the vss is butted up against the yoke and if loose will slip and cause a false reading. Then the next step is to rewire. The speedo works fine correct?
Customer: replied 8 months ago.
Yep checked the tone wheel earlier. And is tight with no movement.Speedo works fine.Photo is of the ECM pins I checked ohms across.Wasn't connected to VSS when I did.
Expert:  go-west.. replied 8 months ago.

What did you get when you ohmed and the ecm plug ??

Customer: replied 8 months ago.
Checked the plug. Can't get a reading. Key on and key off.Behind the speedo at a connection
Get 2.25 k Ohms back to the VSS on yoke. Green and Black wires twisted up
9.99k ohms at connection to Speedo
Expert:  go-west.. replied 8 months ago.
Since you have no reading at the ecm plug that a issue , the next move is to rewire from ecm to vss
Or in this case you could run a new twisted pair from ecm to speedo head but spice into wires
Let me know how you do
Customer: replied 8 months ago.
Which wire at the back of speedo?
Customer: replied 8 months ago.
I think I have worked out the followingThere is 6 Wires
Black - To VSS
Green - To VSSYellow - To ECM
Blue (Pink Stripe) - To ECMRed (Orange Stripe) - Power for dash light
Black (Orange Stripe) - Power for dash light
Expert:  go-west.. replied 8 months ago.


Make sure the wires that you run are twisted,min 1 twist per inch

Customer: replied 8 months ago.
Rewired from ECM to Speedo with twist ed wire. No changeOn first drive, I forgot to plug the VSS wire behind the speedo. Speedo didn't work. But everything else was the same. Engine warning light at 1550 rpm. Cruise control still works.Plugged it back in. Speedo works. Everything else the same.
Expert:  go-west.. replied 8 months ago.
Would it difficult to swap the to wires at the speedo to the ecm to confirm it's not a polarity issue?
If no change confirm the resistance at the vss is the same at the pins at the ecm
Note after the pins are swapped. Be sure to road test..Thanks
Customer: replied 8 months ago.
Swap wires from ECM over at Speedo. No change.
9.95k ohms at the VSSWe had a thought of Replacing th Cam Shaft sensor, thinking we may be chasing the wrong end? your thoughts?
Expert:  go-west.. replied 8 months ago.

this is the 84/01 Troubleshooting

You will will see that we have gone through is.Please do not replace the cam sensor,not related.Wow this is a hard one !!

Customer: replied 8 months ago.
Sorry, I meant the Crank sensor.Given that the Cruise works without the speedo working, and the signal comes from this sensor. Are this the sensor that isnt matching the speed sensor??
Expert:  go-west.. replied 8 months ago.

your resistance and the vss was 9.95k

the spec is 100 to 4k

im wondering if the ecm doesn't like that out of spec resistance

the wiring only total resistance was at less that 5 ohms,correct ??