Will a bad TPS prevent cruise control operation? FIXED!
#2073298
05/14/16 03:20 PM
05/14/16 03:20 PM
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Joined: Jan 2003
Posts: 28,069 Irving, TX
feets
OP
Senior Management
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OP
Senior Management
Joined: Jan 2003
Posts: 28,069
Irving, TX
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I'm troubleshooting the cruise control on my 92 D250. The FSM makes mention of codes 34, 15, and 11 in the speed control section but not 24 (TPS).
I know the TPS is shot. That's why I use governor pressure to trigger OD.
There hasn't been time to thoroughly test the electrical function. I was hoping Saturday would be slow enough for me to play with it but I haven't been able to yet.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: Will a bad TPS prevent cruise control operation?
[Re: feets]
#2073328
05/14/16 04:07 PM
05/14/16 04:07 PM
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Joined: Jan 2003
Posts: 28,069 Irving, TX
feets
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Irving, TX
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Oops!
I should have specified that this is a Cummins with mechanical injection. Only the automatics have a TPS. It is used to throw the OD and that's it as far as I can tell.
The 5 speed trucks do not have a TPS.
Cruise is not mentioned in the Powertrain Diagnostics Manual. My factory service manual makes no mention of the TPS in the speed control diagnostics.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: Will a bad TPS prevent cruise control operation?
[Re: feets]
#2073722
05/15/16 08:45 AM
05/15/16 08:45 AM
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Joined: Dec 2014
Posts: 5,931 ohio
ruderunner
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master
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ohio
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On the diesels, cruise is getting an RPM signal from the crank sensor. That's the 91-93 trucks, not positive on the 89-90.
If the CPs is out you'll also be missing AC and charging.
Verify vacuum to the can on the fender.
Clockspring and switches are common problems oon these.
Angry white pureblood male
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Re: Will a bad TPS prevent cruise control operation?
[Re: feets]
#2074691
05/16/16 07:44 PM
05/16/16 07:44 PM
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Joined: Jan 2003
Posts: 28,069 Irving, TX
feets
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Senior Management
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Irving, TX
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Thanks for the suggestions. I found a dodgy resume switch on the steering wheel. It is no longer available so a friend and I took it apart and ordered a replacement microswitch for 59 cents. I've questioned my clock spring in the past when the horn was iffy but that hasn't been a problem lately. Once the repaired switch goes back in I'll move to the next step in line. The vacuum is great. It feeds directly off the brake booster and that was replaced not too long ago. The CPS is okay since I have no problem with the A/C or charging.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: Will a bad TPS prevent cruise control operation?
[Re: feets]
#2078573
05/23/16 12:39 AM
05/23/16 12:39 AM
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Joined: Jan 2003
Posts: 28,069 Irving, TX
feets
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Senior Management
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OP
Senior Management
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Irving, TX
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The 59 cent switch landed. Kirk enjoys electrical fiddly bits more than I do so he soldered it onto the board for me. We got together for some grub tonight and he gave me the repaired switch.
Being kinda curious, I installed it while sitting in the parking lot of the restaurant. I had cruise control on the way home! Of course that only involved a half mile or so on the freeway so I diverted in order to play with it a bit longer. The truck didn't want to resume after I hit the brake pedal but all other functions worked fine.
The brake switch is touchy and has occasionally left the brake lights on so I imagine it may be at fault there.
Other than that, I'm kinda excited to have the cruise control working again. It's been inop for the better part of the last ten years.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: Will a bad TPS prevent cruise control operation?
[Re: feets]
#2078659
05/23/16 04:11 AM
05/23/16 04:11 AM
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Joined: Jan 2004
Posts: 8,343 fredericksburg,va
cudaman1969
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master
Joined: Jan 2004
Posts: 8,343
fredericksburg,va
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Thanks for the suggestions. I found a dodgy resume switch on the steering wheel. It is no longer available so a friend and I took it apart and ordered a replacement microswitch for 59 cents. I've questioned my clock spring in the past when the horn was iffy but that hasn't been a problem lately. Once the repaired switch goes back in I'll move to the next step in line. The vacuum is great. It feeds directly off the brake booster and that was replaced not too long ago. The CPS is okay since I have no problem with the A/C or charging. Clock spring? What is that? I have a recall on my 99 Caravan for that.
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Re: Will a bad TPS prevent cruise control operation?
[Re: moparx]
#2078816
05/23/16 01:54 PM
05/23/16 01:54 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
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Posts: 16,376
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A clock spring connects the steering wheel to the rest of the car. It is a flat multi-conductor cable in a round can under the steering wheel. It replaces sliding contacts.
Opened clockspring picture below:
R.
Last edited by dogdays; 05/23/16 01:56 PM.
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Re: Will a bad TPS prevent cruise control operation?
[Re: dogdays]
#2078895
05/23/16 04:07 PM
05/23/16 04:07 PM
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Joined: Jan 2004
Posts: 8,343 fredericksburg,va
cudaman1969
master
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master
Joined: Jan 2004
Posts: 8,343
fredericksburg,va
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A clock spring connects the steering wheel to the rest of the car. It is a flat multi-conductor cable in a round can under the steering wheel. It replaces sliding contacts.
Opened clockspring picture below:
R. Thank you
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