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Cruise Control 1997 PSD

Hi Guys,

We spoke about this last year but never di get it resolved.

1997 F350 w/ 7.3 auto 2WD. At speeds above 50 mph the speedo needle will have a 5 mph "bounce" to it--irregardless of the cruise being on or off. Once you engage the cc the engine will start to surge--enough to feel it. The faster you go, the more pronounced it becomes. If I hold the speed with the accelerator pedal and take the cruise control off then the surging stops--it only happens while the cc is engaged HOWEVER, the speedo needle will still have the "bounce". Any ideas how to cure? At this point, you really can't use the cc at speeds over 55.

Thanks!!

-- Rebel Racing

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Reply to
swc
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Maybe the cruise control is sensing that bounce of the speedo, and it is causing the surging. Now, if that is true, what is causing the bounce? On models with the mechanical speedo cable, it was often the cable itself that needed to be changed. And in the older units I have seen, this cable often fed input into the cruise control box.

Now, it has been a long time since I have even thought about this sort of thing, and could be totally off base, but maybe others who know more will at least come in and flame my reply ;>)

I havent personally seen this kind of bounce on the electronic speedometers, but I am sure that they have their own faults.

Reply to
<HLS

This is just generic info, as I haven't worked on a Ford truck since '85, but it strikes me that you likely have two separate problems. If the truck is not surging, but the speedo is, then you have a bad speedometer cable (or electrical problem if it doesn't use a mechanical speedo cable).

As far as the truck surging whenever the cruise is engaged, that's probably a vacuum leak, or possibly the diaphragm in the cruise control unit itself is torn. An overall vacuum check is in order.

If the vacuum checks out, then check that there isn't too much slack in the throttle cable that runs from the cruise unit to the throttle.

Reply to
E Meyer

Is the speedometer cable driven? If so I would expect that it needs to be lubed or replaced. The cruise can see the same bounce that you see on the gauge so I would expect that problem will clear up when you resolve the primary issue.

Steve B.

Reply to
Steve B.

I recentlly fixed the CC on my 95 Crown Vic. Might be close enough. There are 2 systems for Ford. Do you have an electronic dash board?

disston.

Oh, my problem was the deactivator switch that senses brake line preasure. It is redundant to the brake light switch as a means to cancell CC. Since the BOO switch works and the unit can be turned off manually at the stearing collum I bypassed the faulty part. My Crown Vic is the electronic system and is completelly differant from the older systems that used engine vacuum.

aloha

Reply to
disston

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