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Airdirect
Active Member
15 Posts |
 Posted - 03/29/2016 : 08:33:37 AM
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Can anyone help me with were to procure a wire schematic for this bus. Our church just purchased it and I am trying to fix an intermittent start problem. It has a DT466E and will start when warm outside, but will not start when cold. The only code set is 626.
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slippert
Top Member
USA
630 Posts |
Posted - 03/29/2016 : 08:50:52 AM
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| 626 should be ECM power.....unexpected reset..... I would check power feed for ECM circuits from batteries... the conventionals have fuses and fuse holders in battery box that can be problems, I would assume but not forsure if FE have same setup? maybe someone else knows for sure.... Also seems like if it was fuses or fuse holder temp wouldn't matter either... could be ecm relay not functioning when cold that does happen... again someone else might be able to give you location of those relys on an FE model... |
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Airdirect
Active Member
15 Posts |
Posted - 03/29/2016 : 10:27:29 AM
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| Thanks, I will check the for the fuse. I did notice that while cranking the engine, the engine warn and oil pressure lights both flicker. The starter cranks the engine normally and the battery appears to be strong. I do believe the ECU is losing power during the start sequence. |
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eddo
Advanced Member
USA
311 Posts |
Posted - 03/29/2016 : 11:15:37 AM
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can you define warm and cold?
are we talking below freezing temps? or like me- cold is anything below 60. lol |
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Airdirect
Active Member
15 Posts |
Posted - 03/29/2016 : 6:13:43 PM
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| Cold is 55 degrees. I found a loose connection on the positive battery terminal. The red accessory wire (40A fuse) had a bad terminal end on it. Fixed that and was able to clear the 626 code. The bus starts normally. I now have another problem. After it runs for a few minutes I get the amber engine warn light. Checking the code it is 131, accelerator position signal low. Trying to trace out the wires between the pedal assembly and the ECM, the harness goes through a big black plastic plug in the front bulkhead. I cannot figure out how to disconnect the plug to check for corrosion. Help.... |
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Airdirect
Active Member
15 Posts |
Posted - 03/29/2016 : 10:43:43 PM
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| I found the problem! I started tracing the wires from the accelerator to the ECU. They are all purple in color and easy to trace. From the accelerator they travel to the front left corner of the bus and pass thru the forward cowl via a large black connector. I had trouble figuring out how to disconnect this connector. It has a small bolt on the front side (behind drivers wiper access door) in the middle of the wires. You will have to push the wires to the side to gain access to it. This connector was clean and did not appear to be a problem. Another wire traveled from the accelerator to a relay mounted on the right side of the steering column/dash support (just beside the diagnostic plug and code switch). This wire was pushed back and protruding from the connector. I pushed on it and heard it click into place. I then gave a tug on it to assure it was locked. Once this was fixed, I cleared all codes and the engine started normally and the accelerator worked perfect. After several start and stops I rechecked and did not have any codes present other than 111 (ECU ok). I must have moved the harness during my code checking and allowed this terminal to loose connection. Thanks everyone for you assistance! |
Edited by - Airdirect on 03/29/2016 10:48:05 PM |
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Airdirect
Active Member
15 Posts |
Posted - 04/19/2016 : 6:43:33 PM
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Well my problem is back. The bus ran for several days with no problems then the engine warn light illuminated followed by loss of the accelerator. Engine would only idle. Only code set is 131, Accelerator Position Signal Low. Anybody have a wire diagram and diagnostic procedure I can follow. I do not have any access to technical information other than this forum.
Thanks! |
Edited by - Airdirect on 04/19/2016 6:47:11 PM |
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Fastback
Top Member
1500 Posts |
Posted - 04/20/2016 : 07:45:34 AM
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| Have you checked all the fuses? |
Why yes, the ORIGinal CHARGER is a Fastback |
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Airdirect
Active Member
15 Posts |
Posted - 04/20/2016 : 09:10:42 AM
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| Yes, it has a circuit breaker (APS) #23, I am getting the 12V at terminal F of the accelerator connector. I also have 5V regulated at terminal C. All the other parameters on pins A, B, & D are within specs. Now in the process of using an ohm meter to check the connections between the APS and ECM. |
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Airdirect
Active Member
15 Posts |
Posted - 04/20/2016 : 09:13:51 AM
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Here is the procedure I am following: Found it on the "PowerStrokeArmy.com" web page.
DIAGNOSTICS
There can be various conditions that can cause APS/IVS related issues. As with any performance related fault, a thorough description of the issue, from the operator is critical.
Is the fault sensitive to road conditions, such as rough terrain, hills, etc ?
Is the fault temperature sensitive ?
Does the fault occur, when coming to a stop, or when accelerating or cruising ?
Do any other faults occur at the same time, such as loss of dash cluster, or other in cab accessories ?
Are there faults regarding the IAT (intake air temperature) sensor, BAP(barometric air pressure sensor)?
If any circuit issues are suspected, a thorough visual inspection of all circuitry for shorts, and opens is critical, as intermittent issues are usually caused by wiring faults. Any harness mounting points should be disassembled and inspected. Where harnesses pass by sharp edges, or possible points of abrasion should be inspected and if required, repaired. On 4300, 4400, 7300, and 7400, DT466E/530E , NavPak™ ECM equipped, vehicles chassis' several common harness contact points have been noted. The harness passes by the drivers side edge, of the doghouse opening in the firewall. The harness runs very close to this area, and can cut, and short the harness. At the left rear of the engine valve cover, is a P-clamp mounting of the harness. This clamp, and the surrounding mounting area, can cause harness abrasion, and shorting. The harness is long enough, in these areas, to be relocated, after the repair, to prevent recurrence.
On T444E, DT466E and 530E NavPak™ ECM equipped chassis', when inspecting the ECM connector, remove the orange rubber seal, located in the ECM, being careful to not damage/bend any pins. This seal can mask evidence of corrosion in the ECM. Removal of the red locks in the ECM connector, for thorough terminal inspection, is also recommended.
Whenever connector inspection has been performed, and tested satisfactory, always apply a light coating of dielectric grease upon reconnection, being careful to properly lock connectors.
On 2000,3400,3800,4000FBC,4000 and 8000 models, the metal pedal assemblies can wear over time, causing a timing issue between the APS and the IVS signals. A worn pedal can often be tested by pulling up on the accelerator pedal, with the ignition switch on. If faults codes become active, the pedal assembly is most likely the cause.
If idle validation faults are an issue, testing the ignition voltage supply to the sensor should be performed. Opens, short, corrosion, etc. can interfere with the IVS operation.
COMPONENT/FUNCTION DESCRIPTION
The Accelerator Position Sensor (APS) is a potentiometer sensor. When the APS receives a 5V reference signal and a ground from the Electronic Control Module (ECM), a linear analog voltage signal will indicate a demand for power.
The Idle Validation Switch (IVS) provides 0 or 12 Volts to the ECM as a signal to verify the pedal idle position.
Fault Detection and Management
Detected malfunctions of the APS or IVS sensor circuit will illuminate the WARN ENGINE lamp.
If the ECM detects an APS signal Out of Range High or Out of Range Low, the engine will ignore the APS signal and operate at low idle.
When differences between IVS and APS are detected, the ECM sets an IVS Diagnostic Trouble Code and limits the APS command to 50%.
If differences between the IVS and APS are detected, but the ECM cannot discern an APS or IVS Diagnostic Trouble Code, the engine will operate at low idle only.
Extended Description
International® electronic engines use an electronic accelerator pedal assembly that includes an Accelerator Position Sensor (APS) and an Idle Validation Switch (IVS). The APS and IVS are integrated into one component mounted on the accelerator pedal. The accelerator pedal assembly is serviceable to the extent that the APS/IVS switch can be replaced without replacing the complete assembly.
Accelerator Position Sensor (APS)
The ECM sends a regulated 5V signal through the ECM black chassis connector terminal 3 to APS connector terminal C. The APS returns a variable voltage signal (depending on pedal position) from the APS connector terminal A to the ECM at terminal 8. The APS is grounded from connector terminal B to the ECM signal ground terminal 11.
APS Auto-Calibration
The ECM determines the lowest and highest pedal positions by reading and storing the minimum and maximum voltage levels from the APS. In this manner the ECM auto-calibrates the system for maximum pedal sensitivity. The ECM auto-calibrates when the key is ON, but when the key is OFF, these values are lost. When the key is ON again, this process starts over. When the pedal is disconnected (or new one installed), the pedal does not need calibration, since calibration happens when the key is ON.
Idle Validation Switch (IVS)
The ECM expects to receive one of two signals through the ECM black chassis connector (terminal 27) from APS/IVS connector terminal D:
· 0V when the pedal is in the idle position.
· 12V when the pedal is depressed.
The Idle Validation Switch receives 12V voltage from the ignition fuse. When the pedal is not in the idle position (throttle applied), the IVS supplies a 12V signal to the ECM.
The ECM compares APS/IVS inputs at terminals 8 and 27 to verify that the pedal is in the idle position. If the APS signal at terminal 8 indicates throttle is being applied, the ECM expects to see 12V at IVS terminal 27. If the APS signal at terminal 8 indicates idle, the ECM expects to see 0V at the IVS terminal 27.
ECM Diagnostics
When the ignition is ON, the ECM continuously monitors the APS/IVS circuits for expected voltages. The ECM also compares the APS and IVS signals for differences. If the signals are not what the ECM expects to see, the ECM sets Diagnostic Trouble Codes.
TROUBLESHOOTING
NOTE:
When performing diagnostic tests, be sure to refer to the correct circuit diagram manuals, found on ISIS, for the vehicle you are working on. If working on a vehicle built before October 1, 1998, you will need to refer to a paper/hard copy manual, as they are not in electronic format on ISIS®. However, the electronic versions, found on ISIS®, of the Engine Diagnostic manuals, and Electronic Control System Diagnostic forms will also provide you with circuit diagrams.
ZTSE 4486 - APS /IVS Breakout Tee
CIRCUIT DIAGRAMS
NavPak™ Controller APS /IVS Circuit
Connector Voltage Checks
(Check with Sensor Connector disconnected, and Ignition Key On)
Test Points Specification Comments
A to GND < 0.25V If greater than 0.25V, signal is shorted to VREF or B+.
B to GND 0V Signal ground no voltage expected.
C to GND 5 ± 0.5V Voltage > spec, wire shorted to B+
D to GND < 0.25V Voltage > 0.25V, IVS signal wire shorted to VREF or B+
F to GND 12V ± 1.5V Voltage < 10.5V check circuit for open or resistance.
Harness Resistance Checks
(Check with breakout box installed on Chassis Harness and ZTSE-4485 - APS/ IVS Break Out Tee Connected to Chassis Harness Only)
Test Points Specification Comments
#8 to A < 5 ohms Resistance from 60 pin connector to harness connector - APS signal.
#11 to B < 5 ohms Resistance from 60 pin connector to harness connector - Signal ground.
#3 to C < 5 ohms Resistance from 60 pin connector to harness connector - VREF.
#27 to D < 5 ohms Resistance from 60 pin connector to harness connector - IVS signal.
F17 to F < 5 ohms Resistance from VIGN. power to harness connector.
Operational Voltage Checks
(Check with ZTSE-4485 - APS/ IVS Break Out Tee installed and APS/IVS sensor connected)
APS Test Points
(+) #8 to (-) #11 IVS Test Points
(+) #27 to (-) #11 Operational Signal Checks
(Check with breakout box installed on ECM and Engine Harness)
Position Voltage % APS Voltage % APS Comments
Low Idle 0.64 - 0.66V 0 % 0 V 0 % IVS toggles just off idle.
High Idle 3.84 - 3.86 V 98 - 102% 12 ± 1.5 V 98 - 102%
NOTE:
If any of the circuit readings are not within the required specifications, keep in mind, that the IAT (Intake Air Temp.) sensor, is spliced with the signal ground and BAP (Barometric Air Press.) sensor circuits are spliced with the 5 volt reference circuits, of the APS/IVS. These circuits should also be inspected, as they can affect the APS/IVS function/readings. |
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Airdirect
Active Member
15 Posts |
Posted - 04/20/2016 : 10:06:39 PM
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| Checked the wiring using a fluke ohm meter. Term A to pin 8 was 2 ohms, term B to pin 11 was 2 ohms, term C to pin 3 was 2 ohms, term D to pin 27 was 3 ohms. Fuse 23 to Pin F was 2 ohms. I was able to swap the APS from another bus and the problem stayed with this bus, the other bus runs fine with the swapped APS. I determined it must be a problem with the ECM. I disassembled the ECM and and discovered that pin 27 had a broken solder joint where it solders to the PCB. I re-soldered pin 27 and re-assembled the ECM. The accelerator now works, however I was not careful enough and got the base of two of the transistors touching when I re-assembled the ECU. This caused one of the transistors to fail. I now have a code 515 - Bank 1 High Side Short to ground or VBAT. The engine only runs on three cylinders. I will now try and find a replacement transistor, hopefully none of the downstream components were damaged by the short. Anybody attempted ECM repair? Did you have success? |
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Airdirect
Active Member
15 Posts |
Posted - 04/28/2016 : 1:53:20 PM
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| I was able to find the shorted component, it was a BUZ31L N channel mosfet. This part is no longer available but crosses to a IRL640 Vishay mosfet. Removed the defective part and soldered the new one in. Reinstalled the ECM and all is good. Drove it on a 20 miles test run and the accelerator problem returned. I have read on the forums that IC made an overlay cable to fix this problem. My take on the problem was the large power cables which carry high amperage were causing induction/noise problems into the sensitive low voltage signal coming from the APS. I decided to create my own overlay cable. I disconnected both harness plugs at the forward cowl (behind driver wiper access door). I then dissembled the harness from these plugs to the ECM (lower plug). I separated the wires going to each plug and taped the bundles. I then re-inserted these two bundles into the plastic wire loom. This loom originally included large power wires that carry charging current from the alternator (via starter) to the power distribution panel (beside driver seat). I removed these heavy power wires from the loom and tie wrapped them separately away from the remaining loom. This appears to have fixed the APS sensor problem (Code 131). Bus is back on the route, will keep folks posted if the problem re-appears. |
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Airdirect
Active Member
15 Posts |
Posted - 05/09/2016 : 3:56:21 PM
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| Bus is running fine, no more APS or ECM problems. Hopefully it will continue. I will keep the post updated if new issues arise. |
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2003 IC AmTran FE Electrical Diagram
