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Tool Hut
Tool Hut, ASE Certified Technician
Category: Cadillac
Satisfied Customers: 515
Experience:  Owner of a mobile diagnostics company assisting auto technicians with difficult vehicles
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I need help getting my cadillac to run on idle. it only runs

Customer Question

i need help getting my cadillac to run on idle.
it only runs or starts if you have your foot on the gas pedal at all times.
Submitted: 1 year ago.
Category: Cadillac
Expert:  Tool Hut replied 1 year ago.

Hi, My Name is***** have over 20 years experience repairing vehicles. I am a ASE Certified Master Auto Technician. I am confident we can resolve your problem together.Please remember I don't know your skill level. I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies to get to a satisfactory resolution.I also try to give all of the information you may need expecting a positive rating. If there is any reason I cannot get a positive rating please let me know.

Did you have this problem prior to repairs listed?

Customer: replied 1 year ago.
i bought the car used, it sat for 3 years, i bought the car with this problem. I can make a video of what happens if that helps you too.
Expert:  Tool Hut replied 1 year ago.

Do you have a fuel pressure gauge. or a scanner?

I would like you to look at TPS voltage with engine off and key on foot off gas pedal and again wide open.

Long and short term fuel trims when its running

Customer: replied 1 year ago.
i scanned and have some codes
THESE ARE CURRENT CODESu1000
U1128
B1591
83382
B0429
B1004
B1420
P0122
P0300
P0410
P1359
P1360
P1571
P1644
B1586
B3832
C0635
C0640
B0065
Customer: replied 1 year ago.
P0122 says that the throttle position voltage is low ? could this be the issue?
Customer: replied 1 year ago.
i don't have a multi meter, is there still a way to test the voltage? should i go buy one?
Expert:  Tool Hut replied 1 year ago.

A meter is the best way. They are inexpensive

Customer: replied 1 year ago.
ok i will get one on monday.what should the voltage say on the tps? lowest and highest?how do i test it? what do i put the multimeter to? ohms?what do i put the multimeter probes on?
Expert:  Tool Hut replied 1 year ago.

The P1359 and P1360 indicate an ignition module fault. Looks like you may have multiple problems. Lets tackle them 1 at a time. The P0122 is the one I suggest starting with.

Does your scanner have TPS Voltages?

Key on and engine off it should be .5 volts and with the throttle pushed to floor should be 5 volts

Customer: replied 1 year ago.
i will buy a multimeter on monday. My scanner doesn't have voltage tester so i will buy a multimeter within 2 days.
Customer: replied 1 year ago.
the battery is in the back seat, so do i still need to have the ground connected to the battery? i don't know how i can if the battery is in the back seat.
Expert:  Tool Hut replied 1 year ago.

There is a fuse box under the hood has a positive cable hooked to it.

Customer: replied 1 year ago.
there are 3 wires i see located on the TPS. which one do i test?so i put the negative probe of the multimeter to the positive cable of the fuse box?
Expert:  Tool Hut replied 1 year ago.

Do these tests with the key in the on position but leave the engine off

Place the red cable on positive cable and check the black wire. Should be around 12 volts.

Now put the black wire on a ground and check the gray wire should be 5 volts.

If these are OK leave the black wire hooked to ground and plug connector into TPS and use a Tpin or something simliar and check blue wire for voltage at throttle closed should be .5 volts. Now crank throttle open and it should go to 5 volts wide open. if the readings are any different let me know and I will advise on next steps

Customer: replied 1 year ago.
ok i will get the multimeter on monday morning and give these tests a try and then let you know.
Expert:  Tool Hut replied 1 year ago.

I would stop and get some Tpins at a fabric store as well as I may have you doing additional tests.

Customer: replied 1 year ago.
what size?
Expert:  Tool Hut replied 1 year ago.

The large tpins. You want them stiff.

Customer: replied 1 year ago.
1.75" ?
Expert:  Tool Hut replied 1 year ago.

Yes, I think that would be fine. Like I sadi want them stiff but bendable

Customer: replied 1 year ago.
alright i got the multimeter. Here are some pictures of the meter, but more importantly a picture of where the TPS is. It is too far away from the fuse box to get to the positive, i unplugged the tps but haven't testing anything yet because i don't know how,
what setting to put on my multimeter, then where to test. the cord to the TPS was taped alot it looks like. what do i do?
Expert:  Tool Hut replied 1 year ago.

The one is a picture of the meter and I have no idea what the others are.

On your throttle housing you should have a tps looks something like picture I attached.

Customer: replied 1 year ago.
yeah i know where the TPS is.but something happened and i don't know what, after unplugging it, i needed to plug it back in in order to get my keys out of the ignition. I tried getting the keys out and they won't come out, then i tried putting it in the on position but no lights are coming on and no sign of battery. i can't get my key out of ignition. What do i do???
Expert:  Tool Hut replied 1 year ago.

Did your battery go low?

Is your ignition on the dash?

Customer: replied 1 year ago.
the ignition is connected to the wheel, the battery might have been low. what do i do now? the battery light has been blinking for awhile but when it was tested by the car it said "14.6 volts ok."
Customer: replied 1 year ago.
i was also testing fuses and a relay fell out. it was known to the car as start 1.
when i tried reinserting it nothing changed, i think the relay is bad as i have had problems starting the car before. I ordered a new relay of the same model and kind. the prongs on it were also orange corroded a little
Expert:  Tool Hut replied 1 year ago.

It is likely that your fuse box is corroded then. You may need a fusebox.

Customer: replied 1 year ago.
i ordered the new relay, the others fuses looked fine. The car was having problems starting once every few dozens starts, it would sometimes take an hour for it to try and start again, i hope this solves my issue as this was so loose when it came out, no resistance at all pulling it out.
Customer: replied 1 year ago.
it will be here on thursday, since the key is locked for now, will my battery be draining during this or no? should i disconnect the battery?
Expert:  Tool Hut replied 1 year ago.

disconnect battery. or put charger on it as this could damage ECM when voltage goes low

Customer: replied 1 year ago.
ok i will go disconnect it right now,
Expert:  Tool Hut replied 1 year ago.

let me know when your relay arrives. You may need to tighten your relay connections

Customer: replied 1 year ago.
how do i do that?
Customer: replied 1 year ago.
this is what i bought.
Expert:  Tool Hut replied 1 year ago.

You will have to reach in with a pick or lift box and tighten connections. Usually you can do it with a pick. Make sure battery disconnected.

Customer: replied 1 year ago.
i put the new relay in. But the car won't start, i think the battery is dead. I tested it with a multi meter and it was 2.0 volts.i think the reason i killed it was because i was only starting the car and not driving it.
should i jump start it?
Expert:  Tool Hut replied 1 year ago.

I would recommend using a battery charger

Customer: replied 1 year ago.
how much is one? what brand do you recommend?
Expert:  Tool Hut replied 1 year ago.

You can get a battery charger for around 50. I would recommend a 2/10 amp automatic. Avoid harbor freight or other discount outlets. I would get one at a parts store or sears

Customer: replied 1 year ago.
alright i got the charger, charged the battery to a start able level. still same problem, i even went to the junkyard and got a different tps sensor and didn't fix it. the voltage was fine on the wires.
Expert:  Tool Hut replied 1 year ago.

Is the key still stuck in ignition?

Customer: replied 1 year ago.
no it came right out. dead battery must have done that
Expert:  Tool Hut replied 1 year ago.

Do you have a solid security light now? I have attached a relearn procedure if yes

Customer: replied 1 year ago.
i reset the computer and the tps code went away. it is still misfiring and still won't idle. while i was looking around i took the engine cover off and found something strange. i attached a picture, this connects to the throttle body as a little tube. I don't know if this will help or not but a screw seems to be in it. Is it supposed to be like this?
Expert:  Tool Hut replied 1 year ago.

That is a vacuum line that someone has plugged. I cannot tell by the picture where it goes. If you can find it plug it in and I am pretty confident you will determine why it is disconnected

Customer: replied 1 year ago.
where should i start looking?
Expert:  Tool Hut replied 1 year ago.

Look for a port that has a cap on it. I cannot locate a diagram. There should be a diagram under the hood

Customer: replied 1 year ago.
ok i fixed the plug issue but still won't idle.

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