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Old 01-16-2017, 11:55 AM   #1
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Throttle and start issue

If someone would like to direct me to where this subject has been addressed, I will gladly do the research myself...having said that,

1998 3800 DT444E

Throttle issue.

Last week, a helper started pulling wires under the dash/kick panel in my absence looking for a buzzer. All gauges cycle, but nothing responds when the key is fully turned. No start.

Checked firewall start relay.
Checked all the relays under the dash I could see.
No apparent loose wires.
Bypassed the neutral switch on the tranny.
Checked the Throttle Pos sensor on the pedal.
Temp wired in a push-button with a 20AMP inline fuse from the ignition switch.

The bus starts and runs well; however, when throttle reaches 1000 RPM, it goes back to idle with no further response. Got an engine light. Resets after each new start.

Hooked up a Prolink and got codes referring to the APS and IVS. Makes sense, but don't know where to start looking. Assume the two issues are related.

I have no schematic. Like Freightliner, there are many yellow colored wires to follow. I would be grateful for any direction.

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Old 01-16-2017, 12:00 PM   #2
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What are the specific codes that you are seeing??
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Old 01-16-2017, 12:24 PM   #3
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Thanks, Steve

I am in the office right now, but I believe that I received 2 codes:

SID 230 FMI 11 and PID 91 FMI 7

I did not write them down. This is from memory. I will run over this afternoon and validate the numbers if you like.

Thanks for the quick response.

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Old 01-16-2017, 03:06 PM   #4
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Not super clear on the issue but basically youre saying if you hit the gas, it won't rev? Assuming its a drive by wire throttle (no physical connection from pedal to engine) you checked the TPS and said it was good? I'd start looking for a wiring fault between the TPS and the engine computer or wherever the wires go from the pedal.
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Old 01-16-2017, 05:31 PM   #5
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if you are using a prolink or are using the Navistar ServiceMaxx J1939 software you should be able to depress the pedal and see the TPS % go up and down..

part of your post says the bus wont start, another part says it starts withy no throttle response.

the TPS is in the pedal itself.. follow the wires from the pedal itself to see if any have been cut..

yes this is a drive-by-wire engine.

there is a DT-466E and a T-444E.. not sure which you have? you marked DT-444E.

the control system is ver ysimilar for both..

if ther bus wont start at all its usually where you disconnected a door sensor / Buzzer and the yare wired to the starting circuit so if an emergency door or window is open a buzzer will sound and the bus wont start..

if the bus does start but just wont respond to throttle pedal thats when you start looking for issues in the wiring from the throttle pedal itself.
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