Yo,
For tonight,let's talk about DTC 452, Erratic Harsh Shift; Short Circuits, Common Locations TSB 95-02-11 on 94-95 Bronco & Trucks; SEE C, E4OD Harsh Shifts & D, Code 452 - see Poss. Short Locations: 1. Driver's side A pillar trim screws may have been installed thru da 17K745 Sun Visor wire assy & .. bullet connector; 3. Scuff plate screws (driver's side) may pinch the 14A504 wire assy; 4 14401 wire assy may be trapped/pinched between Half car beam & instrument panel attachment (repeated as #7. the wire harness may be pinched/shorted behind the dash where the 14401 wire assy may come in contact w/a sharp edge on dash panel wall 5. shift cable assy near tranny may chaf the wire harness; the wire harness; 7. repeated above..brake pedal-to-dash panel wall weld
Source: by Ford
@
http://www.revbase.com/BBBMotor/TSb/DownloadPdf?id=41117
also see
DTC 27, 29, 452, P0502, P0503, PO716, PO718; Insufficient input from VSS.; "...A more difficult problem to identify is a VSS that works, but sends out the wrong signal for a given vehicle speed. In some cases, a wrong reading from the VSS may still cause a code to be set. For example, if the VSS signal tells the computer the vehicle is traveling 60 miles an hour, but the throttle position sensor and MAP sensor tell the computer that the engine is idling, the computer will be confused. And a confused computer should set any of the following codes: Ford 27, 29, 452. On a vehicle that uses the VSS as a safety device, a defective sensor may send out a wrong "too fast" signal, shutting down fuel flow at the wrong time. Although this doesn’t happen often, it can be a difficult problem to identify. The customer will probably describe it as a random or intermittent sudden loss of power and poor performance, only to have the engine resume normal operation. Routine diagnostic checks of the engine in the shop won’t show any problem because there isn’t a problem with the engine or the ECM..." read more
Source: by wellsmfgcorp.com
http://redirect.viglink.com/?format=go&jsonp=vglnk_146366962315713&key=6ed47b392b9edfe394b9e89b72717104&libId=ioedc0y101000bgv000MAbkp6y6zp&loc=http%3A%2F%2Fwww.fullsizebronco.com%2Fforum%2F21-noobie-bronco-tech-questions-flame-free-zone%2F336666-obd-code-111-10-212-332-452-636-327-a.html&v=1&ref=https%3A%2F%2Fwww.google.com%2F&title=93%20Bronco%20Hard%20Shift%20Code%20452%20-%20Ford%20Bronco%20Forum&txt=http%3A%2F%2Fapi.viglink.com%2Fapi%2Fclick%3Ffor...erpoint4_2.pdf&out=http%3A%2F%2Fwww.wellsve.com%2Fsft503%2FCounterpoint4_2.pdf
someone else recently had the "14401 wire assy may be trapped/pinched between Half car beam & instrument panel attachment (repeated as #7. the wire harness may be pinched/shorted behind the dash where the 14401 wire assy may come in contact w/a sharp edge on dash panel"
And Turbo Ghost wrote about non-Ford VSS issues @
"I don't know about different lengths but, when I replaced mine, the one from autozone didn't fit right. The one from Ford fit perfectly and solved that aspect of my problem. There was a difference in the way they tightened against the differential. The autozone one got pulled at an angle and the Ford unit went in straight."
btw, Ford often refers to VSS AND as the RABS SENSOR
DS1 DIAGNOSTIC TROUBLE CODES (DTCS) 29 AND 452: CHECK PSOM RESISTANCE
Continuous Memory DTC 29 indicates that during the last 80 warm-up cycles, the PCM detected an error in the PSOM output signal. DTC 452 indicates the PCM detected an error in the PSOM output signal during the last 40 warm-up cycles.
Possible Causes:
Damaged Rear Anti-Lock Brake System (RABS).
Damaged PSOM.
Damaged harness circuits.
Damaged PCM.
Key off.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box, leave PCM disconnected.
Measure resistance between Test Pin 3 and Test Pin 6 at the breakout box.
Read more
instead of breakout box, go to the EEC CONNECTOR pin or other instead; for instance - Measure resistance between Test Pin 3 and Test Pin 6; EEC Connector Pin 3 is VSS +
in 6 is VSS -
To help troubleshoot;
EEC IV Connector Pin Diagram by Ryan M (Fireguy50)
http://web.archive.org/web/20131229163930/http://oldfuelinjection.com/images/eec04.gif
EEC Connector Pin Outs LEGEND, Bronco & Ford Truck & Van: 4.9, 460, 5.0, 5.8; by Ryan M (Fireguy50) at
http://web.archive.org/web/20120118104425/http://www.oldfuelinjection.com/truckpinouts.html
......
111 is the pass code, could be ????
...
311 koer Thermactor air system inoperative (right side)
"...The computer determined that for some reason the fresh air injection from the Thermactor system was not present. There are several components that make up this system. The initial component is the smog pump. The first checks I would make are the hoses and plumbing from the smog pump back to the diverter valve (behind the pass. cylinder head) and then on to the crossover pipe at the back of the heads and down to the catalytic converter. The check valves that are at the center of the cross over pipe and the top of the metal tube from the cat are often the culprits as they can and do snap in half as the get old. If the plumbing looks to be in good order we can discuss the slightly more complicated aspects of the system. The diverter valve also has two vacuum lines running to it. Make certain they are in place and intact. (Computer needs to be able to control the flow of fresh air by the Thermactor system)..."Source: by greystreak92
DTC 311, 312, 313 & 314; "...311 and 314 indicate the Secondary Air Injection system is inoperative. DTC 312 indicates that Secondary Air is misdirected. DTC 313 indicates that Secondary Air is not being bypassed when requested. Possible causes: Visually inspect vacuum lines for disconnects in the AIR system. Visually inspect for proper vacuum line routing. Refer to VECI decal. Visually inspect Air Pump for broken or loose Air Pump Belt. Refer to Section 13A for adjustment/replacement.
Source: by Jim
See my vacuum leak test in post #20 at
http://broncozone.com/topic/23994-90-58l-getting-continuous-code-33-and-running-code-44/?p=125535
...
DTC 538 Insufficient RPM change during dynamic response test. "...This is another code generated when the dynamic response or "goose" test as some refer to it is not performed during the KOER test. The KOER test requires that after a certain length of time the throttle be opened to bring the idle above 2000 rpm for a short period of time. If the dynamic response test is not performed or the rpm's do not peak ABOVE 2000 rpm's this code will be generated. (Computer needs to compare changes in sensor readings at different RPM's to determine system operation and efficiency)..."
Source: by miesk5 at Ford Bronco Zone Forums
...
DTC 536 - Brake On/Off circuit failure / switch not actuated during KOER test or shorted to ground
Source: by miesk5
Or...
The brake on/off switch tells the powertrain control module when the brakes are applied. The switch is closed when the brakes are applied and open when they are released. The PCM uses this signal to disengage torque converter clutch when brake is applied.
Symptoms: Failed on or not connected Torque converter clutch will not engage at less than 1/3 throttle. Failed off Torque converter clutch will not disengage when brake is applied.
...
DTC 632 -IGNOREl O/D Cancel switch, Overdrive cancel switch did not change state during KOER; is possibly the result of the test being done incorrectly. When you do a KOER test, you need to do a Dynamic Response Check is used to verify operation of the Throttle Position Sensor (TPS), Mass Air Flow (MAF), Manifold Absolute Pressure(MAP), and Knock Sensor (KS) during a brief wide open throttle condition. The famed "Goose test".
