I have a 89 Aerostar that is giving me trouble with the cruise control. Let's say I set the cruise at 70. The van will slowly go to 75 then quickly go back to 70. The van will keep doing this until I turn off the cruise control. Which part should I look at replacing first. I am getting set to go on a long trip and this get's pretty annoying.

 

My 89 has that problem - although it is intermittent.
Some days I hit the cruise and it runs liek a top - locks me in at say 80 clicks, and wavers no more than a click or two on grades. Other days I hit the cruise at 80, and it dropps to 75, accels hard(and with a race exhaust on this thing, that roars good) to about 85 or so, then drops to 75 again. Nasty. Is yours the same, being jumpy and intermittent? If so then the culprit is likely a loose wire on the speed sensor (if there is such a thing - I am not too keen on how the whole cruise operates, and my Haynes book has gone astray) - if it is always this way, then chances are the sensor is shot..

My 2c for what it is worth (and that is Canadian bux, so not alot.. LOL)

Zarin

 

I tested the wires going to the sensor this weekend. I do not have a problem with the connection. I changed the sensor and I still have the problem I am going to check the actuator and the vacuum lines when I get back from my trip.

 

Most likely it is the MAF/MAP sensor. I had the surging problem (more like take-off!) and had mine replaced. Of course, it does not work again ... I have not bothered to replace it the last 70K or so.

There "was" a TSB or something about replacing the older style with a newer style, which was done on mine.

(Our 95 Aerostar has 187K - A4LD finally gave up the ghost - first major component failure, even has the original starter and alternator, it has been a great vehicle!).

 

[updated:LAST EDITED ON 03-Dec-02 AT 03:18 PM (EST)]>I have a 89 Aerostar that is giving me trouble with the
>cruise control. Let's say I set the cruise at 70. The van
>will slowly go to 75 then quickly go back to 70. The van
>will keep doing this until I turn off the cruise control.

I, too, have an '89. I had to go through the whole CC shebang when I bought it.

The CC servo unit (the part that does the work, disc shaped, behind the battery) has two CC position feedback potentiometers built in, and they do not appear to be very high quality. Though the manuals give no information on the internals of the servo unit, it *can* be dissassembled and cleaned.

I suggest that one of the pots is getting a weak spot, so the info being sent to the CC module is intermittantly faulty.

Both the AllData CD and the factory manual give test procedures for the servo unit.

My servo unit was so crapped up that I bought a junkyard one instead of trying to refurbish it. It cost me $20 for the servo unit, and I transferred my old cable. Very easy to replace.

BTW, the CC control module on our rigs (located inside, above and to the right of your right foot) *is* adjustable for take-up. Inside, there's a tweek pot. I've got mine dialled in so that it's perfect: press "Set" and it neither speeds up nor slows down.

Regards,
Al S.