2003 Tahoe shuts off randomly

Gavin Strunk

TYF Newbie
Joined
Aug 15, 2022
Posts
4
Reaction score
2
Hey everyone, a relative of mine has an 03 Tahoe that I'm trying to get back on the road that's been having a bit of a mystery issue. It runs and drive seemingly without issue but then it suddenly shuts off. I was on a test drive and everything seemed to be going well until I went over a bump and it stuttered. Wanting to recreate the issue, I turned and braked while going over a bit of a bump and sure enough it shut down completely. The codes showing up are P0120, P0220, P1516, and P2135. I personally think there's clearly something between the pedal and throttle body that's just not working right, whether that be a connector, wiring, or even the sensors themselves. If anyone has had an issue like this before it would be great if you had any input on what fixed your vehicle or any helpful troubleshooting tips, thanks.
 
OP
OP
G

Gavin Strunk

TYF Newbie
Joined
Aug 15, 2022
Posts
4
Reaction score
2
Hey everyone, a relative of mine has an 03 Tahoe that I'm trying to get back on the road that's been having a bit of a mystery issue. It runs and drive seemingly without issue but then it suddenly shuts off. I was on a test drive and everything seemed to be going well until I went over a bump and it stuttered. Wanting to recreate the issue, I turned and braked while going over a bit of a bump and sure enough it shut down completely. The codes showing up are P0120, P0220, P1516, and P2135. I personally think there's clearly something between the pedal and throttle body that's just not working right, whether that be a connector, wiring, or even the sensors themselves. If anyone has had an issue like this before it would be great if you had any input on what fixed your vehicle or any helpful troubleshooting tips, thanks.
If anyone has any questions that they think might help diagnose the issue, I'm happy to answer them.
 

Fless

Staff member
Super Moderator
Supporting Member
Joined
Apr 2, 2017
Posts
6,716
Reaction score
11,961
Location
Elev 5,280
It's all relative -- pun intended -- but "your" '03 is DBW - Drive By Wire, meaning that the throttle body is controlled by the pedal position sensor, and the throttle position sensor on the the throttle body. I know that others will have ideas, but here are a couple I'll throw out there.

One diag that should be done is to graph the pedal position sensor (with a scan tool) to see if it is smooth over the range or if it has dropouts.

Also, the wires near the throttle body can have a tendency to rub and break internally; visually inspect them from the TB as far back as you can, paying close attention to the insulation. One or more wires can be broken under the insulation, so a hands-on inspection is due.
 

Sam Harris

Supporting Member
Joined
Sep 26, 2018
Posts
6,293
Reaction score
11,881
Location
Denver
In addition to the sage advice provided by @Fless , these rigs are well known for ground problems. So if you don’t find any problems there, I’d recommend taking a close look at the main grounds on the rig. Especially under the driver seat, and in the engine compartment.
 

rockola1971

Full Access Member
Joined
Dec 29, 2016
Posts
1,818
Reaction score
1,746
Location
Indiana (formerly IL)
What does "shut off" mean? Engine just die? Lose all electrical meaning the dash lights, radio...everything just goes blank like the key was turned to off position? Or????

Typical on the DBW setup when there is a error between throttle position at the pedal and the throttle body the PCM will put you "redeuced engine power" mode which puts the engine at Idle and it will display "Reduced Engine Power" on the Instrument Cluster too. This is a safety to prevent throttle runaway and also to show that you have a problem in your throttle system. Ive never seen it just totally turn the engine off. Shutting down key in the off position then restart usually clears the Reduced Egnine Power mode but the it can come right back depending on what the cause is. I had it on my 05 Denali (bought it that way and used the problem to get it cheap too). Mine was the Throttle Position Sensor had a bad spot in it around 55mph throttle position. The system gets lost and its a built in safety if alot of parameters are not met in the throttle system. There is a TAC (Throttle Actuator Control) Module right on the firewall near the vac brake booster/hydroboost thats soul job is to control the DBW setup.
 
Last edited:

Doubeleive

Wes
Supporting Member
Joined
Nov 7, 2017
Posts
18,033
Reaction score
23,456
Location
Stockton, Ca.
I would try starting it up and pop the hood and start wiggling the throttle body harness around (simulating going over a bump) as already mentioned you may have a broken wire or worn harness, if you are lucky it may replicate the behavior when you find the the bad spot.
 
OP
OP
G

Gavin Strunk

TYF Newbie
Joined
Aug 15, 2022
Posts
4
Reaction score
2
What does "shut off" mean? Engine just die? Lose all electrical meaning the dash lights, radio...everything just goes blank like the key was turned to off position? Or????

Typical on the DBW setup when there is a error between throttle position at the pedal and the throttle body the PCM will put you "redeuced engine power" mode which puts the engine at Idle and it will display "Reduced Engine Power" on the Instrument Cluster too. This is a safety to prevent throttle runaway and also to show that you have a problem in your throttle system. Ive never seen it just totally turn the engine off. Shutting down key in the off position then restart usually clears the Reduced Egnine Power mode but the it can come right back depending on what the cause is. I had it on my 05 Denali (bought it that way and used the problem to get it cheap too). Mine was the Throttle Position Sensor had a bad spot in it around 55mph throttle position. The system gets lost and its a built in safety if alot of parameters are not met in the throttle system. There is a TAC (Throttle Actuator Control) Module right on the firewall near the vac brake booster/hydroboost thats soul job is to control the DBW setup.
Yeah the engine just totally shut off, no interruption to the other electrical systems, when the engine died all the other stuff like the radio was still going without interruption. Rpm just drops to zero. Now what's odd is that it only did it when i went over fairly large jolts otherwise it ran fine. But the first time I noticed the issue it stuttered but didn't totally die. I went from the gravel road to paved highway and it stuttered like it was going to just bog and die. Then it died totally when I was braking and turning into the driveway. I just can't believe the jolts don't have anything to do with it, seems like too large a coincidence that it only wants to start acting up after going over these specific areas. Otherwise I had it going down and back on this decent stretch of gravel road no issues, power was good and it ran just like you'd expect a 5.3 to.
 

MassHoe04

Full Access Member
Joined
Nov 4, 2021
Posts
892
Reaction score
1,336
Location
Western MA
As you describe not losing radio and other noticeable electrical stuff, you still seem to lead me to having lost spark and/or fuel.
Bad ground(s) certainly could momentarily knock out fuel supply or ignition systems, then allow them to act like nothing happened.

From the behavior you describe, I kind of think it is not something like throttle position sensor. I would expect the engine would continue to run if it was.

Sounds more like the injectors, fuel pump, coil packs or a combination of some (or all) of those things getting cut off briefly.

You may have a loose connector or corroded pins on the PCM that gets jiggled when you hit your bumps. That would be enough to disrupt things in a weird way and leave other things running just fine.
Disconnect the harness from the PCM and inspect. Spray it down with some electric terminal cleaner spray and make sure it snaps back on good and tight. See if that does anything...

I would also clean and tighten all main grounds as mentioned above. I would also be giving a good visual inspection on wiring to the fuel pump, injectors, coil packs.
Also check the connector at the PCM to be sure it is clean and snaps in good and solid.
 

Doubeleive

Wes
Supporting Member
Joined
Nov 7, 2017
Posts
18,033
Reaction score
23,456
Location
Stockton, Ca.
As you describe not losing radio and other noticeable electrical stuff, you still seem to lead me to having lost spark and/or fuel.
Bad ground(s) certainly could momentarily knock out fuel supply or ignition systems, then allow them to act like nothing happened.

From the behavior you describe, I kind of think it is not something like throttle position sensor. I would expect the engine would continue to run if it was.

Sounds more like the injectors, fuel pump, coil packs or a combination of some (or all) of those things getting cut off briefly.

You may have a loose connector or corroded pins on the PCM that gets jiggled when you hit your bumps. That would be enough to disrupt things in a weird way and leave other things running just fine.
Disconnect the harness from the PCM and inspect. Spray it down with some electric terminal cleaner spray and make sure it snaps back on good and tight. See if that does anything...

I would also clean and tighten all main grounds as mentioned above. I would also be giving a good visual inspection on wiring to the fuel pump, injectors, coil packs.
Also check the connector at the PCM to be sure it is clean and snaps in good and solid.
all his codes are throttle body codes, there are no others (unless not mentioned) that would suggest fpcm or something of that nature, "usually" you do get a list of random additional codes, none the less it is a good suggestion.
 

MassHoe04

Full Access Member
Joined
Nov 4, 2021
Posts
892
Reaction score
1,336
Location
Western MA
all his codes are throttle body codes, there are no others (unless not mentioned) that would suggest fpcm or something of that nature, "usually" you do get a list of random additional codes, none the less it is a good suggestion.
OK. Thanks. I admit to not taking any time to look up any codes listed by OP... I thought any codes being thrown might just have been the result of power interruption to computer or other parts of the system.

I had a 94 Ford Ranger where the main wiring harness was routed over and attached to the metal inner wheel liner. A couple of wires rubbed through. I found out when I hit bridge expansion joints. The harness would be off the fender liner until I hit the bump. Then it made momentary ground contact and the engine stopped running completely for a second, until the harness lifted itself off the fender liner again. Then it ran fine. A couple wraps of electrical tape took care of that for good.

For a minute, it sounded like the OP's vehicle might have been doing something similar to what my Ranger was doing.
 

Forum statistics

Threads
120,213
Posts
1,660,182
Members
81,379
Latest member
mnewcomb
Top