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Meandmyz · 08-18-2024, 08:29 AM

Hey everyone. I have a 1991 general coach 34.5 on a p30 chassis with a 454 th400 and trying to locate my downshift switch. Nothing at pedal that I could see and nothing on throttle body other then a TPS, manual claims it is under dash above my left foot so today I am going to check but seems wired to be there with a second linkage of sorts.
Anyone have any pics or know the exact location of this switch.
I didn't feel it was downshifting as it should have been on hills when I was wot unless my speed was too fast. I need to install a tach so I can watch my rpm but need to finish getting it perfect before that.
Thanks
Cheers

Wrapped · 08-18-2024, 09:39 AM

Never heard of a downshift switch on P30 or a TH400, sorry.

Meandmyz · 08-18-2024, 10:54 AM

How does the th400 get it's "signal" to downshift while under wot a th350 and th700r4 use a kickdown cable to be adjusted but the th400 uses a wot switch as to my knowledge.
Also described as this per manual also

Meandmyz · 08-18-2024, 10:58 AM

Here are some pics showing where switch should be , the side case of the orange wire for the switch to confirm it's a th400 and also the manual showing where it should be also.

GypsyR · 08-19-2024, 12:15 PM

I've seen some that looked like a throttle stop between the pedal and the floor. You can feel them in action though. Press your foot down and you can feel a smooth 0-95% throttle. Press harder and and you can feel it give that last 5% as the switch is activated.

Worth noting I've seen more than a few of these being driven with nothing connected. When kick down is desired they just grab the shifter and pull it down a gear. I personally prefer my automatics to be more "automatic" than that but if the manual technique is used reasonably, the transmission and vehicle doesn't care at all either way.

Meandmyz · 08-20-2024, 04:40 PM

Thanks for the suggestion and I will check thoroughly tomorrow when at work at the rig. I am a tech (auto and bike) and I will wire up a switch if that's what's needed if I can't find one. I just didn't know if the TBI setups used TPS and manifold vac along with speed to determine the downshift through relay from ECM or something of that nature. But would seem to be overly complicated for a 91. I will peel back the carpet and take a thorough look tomorrow. Thanks