cruise control issues.

[crownv8]

I'm having troubles with a 91 Cressida I have just bought. When I engage the cruise at 100 the auto kicks back out of overdrive and won't re-engage it. If I fiddle will the cruise it will eventually work without kicking back the auto, but when driving it will then kick back again for no reason. As soon as the cruise is disengaged the overdrive drops in.

Has anyone had this problem?? Any Ideas??

The rest of the car works fine. It only plays up if I engage the cruise control.

Cheers,
Shane.

[progkamol]

Hi there,

I not sure I got your situation right or not but this does sound very much like what happening with my mum's car back in Thailand. We have a 1996 Rover 623 GSI automatic. The car have been driven for 102000km without ever using cruise control once due to traffic condition in Bangkok. Anyhow almost 2 years ago we had a long drive to the South of Thailand and we finally have chance to use the cruise control.

From my experience with that car (Rover) at 100km/h in overdrive mode the car is running on 3rd gear. Without overdrive it is running on 4th gear. I drove with overdrive on most of the time and everytime I engaged cruise control the overdrive light gone off adn as soon as I tapped the brake (disengaged) the light came back on. This happen even when I was driving at 80km/h.

So from that I assumed that it is normal for overdrive to drop out when engaged in cruise control. Driving in overdrive does consume slightly more fuel and, according to Rover, the cruise control is design to work to save fuel and maximize performance (eg: right RPM at certain speed does help to save fuel). So I wouldn't worry too much about that if I were you. But again, your car is a Japanese car and the Rover is British so there maybe something different in the design and function.

Hope that info helps

[Gavatron]

WTF! Driving in overdrive consumes LESS fuel cos the engine is doing LOWER RPM!

[progkamol]

WTF! Driving in overdrive consumes LESS fuel cos the engine is doing LOWER RPM!

R U sure??? on the Rover when driving with overdrive (that is with the green light on the dash lid and say OVERDRIVE) the gear changes at higher RPM ... but when driving with the green light on dash that say OVERDRIVE unlid then the gear changes at lower RPM ... but again Rover is a European car so might be different from Jap car ... I've seen my company car (corolla) that have light on dash say "O/D OFF" So I assume that when the light lid up then the car is not in overdrive. This will then be opposite to the Rover as it stated in the owner's manual that when the green light on the dash that says OVERDRIVE lid, you are driving in overdrive.

[Mos]

You could try disconnecting the S2 wire from the cruise control ecu, or at least monitor the wire to see what it's doing.
(OD is engaged by removing power from both solenoids. S2 is connected to both the cruise control ecu and the engine ecu and, I believe, is used by the cruise control ecu to drop it down a gear if it feels it needs to).
Other than diagnosing if it's the engine ecu or cruise ecu that's doing it, this won't help much despite potetntially offering a band aid solution.
Mos.

[rob]

cant help but my parents MX83 did the same thing

[CrUZida]

MX83 wiring digram
http://conceptual.net.au/~peewee/wir...ical%2006a.jpg

The 3 going to the ECU I suspect are the wires you need to check.

They are ECT, S2 and SP2. (same page, over to the left)

As Mos said, S2 is the one you want to check.

[CrUZida]

Oh, something else to check would be the TPS.

If the ECU thinks the TPS is maxed out, it may change down a gear

[crownv8]

Thanks. I'll check those things out when I get a chance.