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Picked up this ol 94 F250 for cheap and rebuilt the 7.3 idi engine. Got her running, the engine is great. The tranmission isnt shifting correctly. Its shifting too soon and wont downshift correctly. Im trying to see if there are any codes for the e4od transmission from the PCM but having no luck. My question is, when you short out the plug EECV in engine compartement to start the code reading process, which light is supposed to flash? The check engine light or the OD light on the shift lever?
So here is my predicament. My instrument cluster is bad in that half of the copper foil pathways are corroded and the check engine light doesnt work. Ive ordered a new circuit board but until i recieve it, i cant determine if the PCM is good or not. I hooked a test light from gray/red wire on datalink connector to ground on battery and recieved no flashes of light at all when doing KeyOnEngineOff test. That should be a alternative way of checking codes, correct?
The truck sat for a long time and lots of moisture has affected things. Ive run many other tests such as checking for power from PCM to TPS and Barometer, PSOM works, speedmeter works with no fluctations, tach works, grounds good, etc.
Next steps to check: pull the PCM out and open up and inspect board, check terminals at PCM, borrow a OBD1 tester from a friend. Thoughts?
I hooked a test light from gray/red wire on datalink connector to ground on battery and recieved no flashes of light at all when doing KeyOnEngineOff test. That should be a alternative way of checking codes, correct?
So performed the test light diagnosis and did not get a single flash of light. This confirms something is wrong with the PCM. I pulled the PCM out and inspected, looks like water was in the connector. No leaking caps, no burns, but i did notice corrosion on the back part of the board where gold connectors are. Ill get those cleaned up and blow everything out and let dry and see what happens.
PCM might be good afterall. Test light doesn't appear to light up on anything with a small amperage. My digital volt meter actually was seeing the fluctuations in voltage as the PCM was sending a codes. Waiting till a get my hands on codereader or get instrument circuit board replaced.
I did find a short in the high mount brake light bulb. I heard that this could cause issues with VSS if its on same circuit?
The bulb got so hot that it super heated the glass and expanded inside the housing. Had to crush the bulb to get it out...
I've never seen a third brake light cause a VSS issue. It can cause issues with the torque converter locking. The PCM looks at the brake light circuit as one of the inputs to lock and unlock the torque converter.
Alright, just got back in from outside. Got a OBD1 scanner hooked up and it pulled 11 code and 23. So basically nothing.
Took her for a spin today , still refuses to downshift automatically when she gets up to operating temp. When she is cold, it seems like it will drop down from 2 to 1 just fine. But once it gets driven more, it seems to stop downshifting. The only way to not to bog down is to slow down till it drops back into 1 first automatically or i have to turn off OD/manually shift it. Im thinking its an internal issue in the trans now...What should my next step be? Take it to my guy that normally rebuilds ford transmissions?
So Mark, i begin inspecting every connection relating to the transmission and found a problem. Looks like the solenoid pack connecter is full of transmission fluid. Im assuming this could be what is causing my issues?
If so and this needs replacing, do i purchase new or reman? Best place?
Ok i confirmed the tranmission fluid in that connector was the problem for poor shifting. I cleaned the connector out throughly and put back together and it shifted better. Ordering a solenoid to replace it. Thank you Mark for the input.