Bouncing speedo needle/hunting cruise ctrl
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Bouncing speedo needle/hunting cruise ctrl
I have a 1994 E150 with 302 and automatic. Several months back, I had the differential replaced with a 4:10 to give better performance and a myriad of other things done, as well.
I noticed one day the speedo needle was jumping and the cruise control hunting. Also, when getting up to about 74, a harsh event like the engine or brakes locking up but no nose diving. I am given to understand that the PSOM sends a signal to the PCM and if a big change, the engine shuts half off half of the fuel injectors and kicks in the converter lockup which is what I am probably experiencing at 74 mph.
Mechanic replaced the speed sensor and went back to check with a guauge that the exciter ring was not distorted. He replaced a wiring connector that I understand to be associated with extending the wiring for a long van body (for speed sensor).
Same problem. So I big the bullet, went to DASH-USA and got a new PSOM, had it programeed for my tire conversion factor and vehicle mileage, installed that today and same problem.
I am beginning the to believe the exciter ring is the problem. Can it be replaced without removing the differential itself.??
Tom
I noticed one day the speedo needle was jumping and the cruise control hunting. Also, when getting up to about 74, a harsh event like the engine or brakes locking up but no nose diving. I am given to understand that the PSOM sends a signal to the PCM and if a big change, the engine shuts half off half of the fuel injectors and kicks in the converter lockup which is what I am probably experiencing at 74 mph.
Mechanic replaced the speed sensor and went back to check with a guauge that the exciter ring was not distorted. He replaced a wiring connector that I understand to be associated with extending the wiring for a long van body (for speed sensor).
Same problem. So I big the bullet, went to DASH-USA and got a new PSOM, had it programeed for my tire conversion factor and vehicle mileage, installed that today and same problem.
I am beginning the to believe the exciter ring is the problem. Can it be replaced without removing the differential itself.??
Tom
Last edited by ttaylor530; Feb 15, 2006 at 11:50 AM.
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1994 E150 5 liter and Auto OD tranny.
I need some new ideas here. I have the bouncing speedo needle deal with the hunting cruise control and it has been known to send a signal to the PCM going around 70 MPH that there is an overrev situation which causes 4 injectors to shut off and a lockup of the converter (which will scare you not expecting it as it is harsh). The PSOM has been replaced, the wiring connectors all checked, speed sensor replaced and the exciter ring checked for trueness. The mechanic has a diagnostic computer that he plugged in and took the truck down the road and said the signal is steady.
I suspected the exciter ring as having a dead spot or maybe damaged when the mechanic replaced the ring and pinion with a 4:10 gear but he says the signal is steady.
Any ideas left here?
Tom
I need some new ideas here. I have the bouncing speedo needle deal with the hunting cruise control and it has been known to send a signal to the PCM going around 70 MPH that there is an overrev situation which causes 4 injectors to shut off and a lockup of the converter (which will scare you not expecting it as it is harsh). The PSOM has been replaced, the wiring connectors all checked, speed sensor replaced and the exciter ring checked for trueness. The mechanic has a diagnostic computer that he plugged in and took the truck down the road and said the signal is steady.
I suspected the exciter ring as having a dead spot or maybe damaged when the mechanic replaced the ring and pinion with a 4:10 gear but he says the signal is steady.
Any ideas left here?
Tom
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I would want to check to vss signal at the pcm. You would need a scope to look at it. If the 94 is like the 92 the diff speed sensor is also used for the anti-lock brakes.
Are you having trouble with that light coming on?
Are you having trouble with that light coming on?
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ABS Light
I had the ABS disabled when I thought the thing was losing its mind and grabbng the brakes. I am going to have that reconnected as I now understand that the problem is not the ABS. I did have an ABS problem and the mechanic replaced the sensor and a wiring connector as the module did not see the sensor. If I remember correctly I was getting a code 3 2 on the ABS light.
All of this begin to happen around the same time as I was sorting out a lot of problem with the van having just bought it. I had the rearend replaced to get better performance and had ABS lights and after that the speedo bounce , etc problem.
All of this begin to happen around the same time as I was sorting out a lot of problem with the van having just bought it. I had the rearend replaced to get better performance and had ABS lights and after that the speedo bounce , etc problem.
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Joined: Jun 2002
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From: Atlanta GA
Have you tried disconnecting the battery for a 1/2 an hour?
I don't know about the 8.8 axle, but, can't you see inside the axle with the VSS removed to see if teeth are chipped or missing? I have seen people break them doing brake jobs/front end work in the front, I do not see how you could break a ring in a rear axle and not know it.
Since yours is new, it probably is not worth checking, but, you could check to see if metal fillings have gathered around the tip. Usually just cleaning the top off solves that problem.
Okay, now this is what I think the problem really might be.
You changed to 4.10 gears. This is the break point for a thicker/thinner ring on most Fords. As the pinion gear gets bigger, the ring has to get narrower. You might have a clearance problem between the tone ring and the VSS and you might have to get a VSS for a 4.10 rear to correct the problem. Do you know the Ford # of the newly installed one and if there is a difference between say a 3.54 and 4.10 VSS?
I don't know about the 8.8 axle, but, can't you see inside the axle with the VSS removed to see if teeth are chipped or missing? I have seen people break them doing brake jobs/front end work in the front, I do not see how you could break a ring in a rear axle and not know it.
Since yours is new, it probably is not worth checking, but, you could check to see if metal fillings have gathered around the tip. Usually just cleaning the top off solves that problem.
Okay, now this is what I think the problem really might be.
You changed to 4.10 gears. This is the break point for a thicker/thinner ring on most Fords. As the pinion gear gets bigger, the ring has to get narrower. You might have a clearance problem between the tone ring and the VSS and you might have to get a VSS for a 4.10 rear to correct the problem. Do you know the Ford # of the newly installed one and if there is a difference between say a 3.54 and 4.10 VSS?
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Vss
Ford lists only one VSS for all years.
The battery was disconnected for over an hour last week when I was replacing the PSOM with a new one programmed by DASH-USA.
The VSS is new, the differential is new and has been drained twice with the mechanic checking the trueness of the exciter ring.
Can a diagnostic computer pick up the AC signal coming from the VSS to see that it is steady while going down the road? BTW, the bounce is always backwards on the needle (from actual current speed, back 4 MPH, current speed, Back 8 MPH, current speed etc.). Most of the time the drop is 3 or 4 MPH but the duration is variable and it also happens under load of acceleration or crusing.
The battery was disconnected for over an hour last week when I was replacing the PSOM with a new one programmed by DASH-USA.
The VSS is new, the differential is new and has been drained twice with the mechanic checking the trueness of the exciter ring.
Can a diagnostic computer pick up the AC signal coming from the VSS to see that it is steady while going down the road? BTW, the bounce is always backwards on the needle (from actual current speed, back 4 MPH, current speed, Back 8 MPH, current speed etc.). Most of the time the drop is 3 or 4 MPH but the duration is variable and it also happens under load of acceleration or crusing.
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