Heavy Equipment Repair Questions? Ask an Expert Now.
Hi my name is Chad. I'm going to try to help you with this.
When you say the engine idles up, what are the RPM the engine is idling at.
Using the auxiliary idle control module (APCM) to engage the PTO, I have linked the PTO with the RPM control. I have set the lower limit @1000 RPM and upper limit @2000 RPM. Also we are getting power at the 12V PTO solenoid when engaged.
OK that might be your problem. You have to have a minimum of 1200 RPM to get the needed 120 psi to activate the clutch.
Also were did they tap the transmission at?
I'm not sure if you have these put these are Fords Manuals for the PTO and Troubleshooting
Also Something else I can across, but I doubt it applies to you.
"The PTO Circuit is wired properly but will not respond". When the vehicle battery is disconnected for extended period the powertrain control strategy "forgets" PTO logic and will not respond to commands for elevated idle until it has had a chance to re-count the number of teeth on the gear-set in the 4R100 automatic transmission (36-teeth for non-PTO 4R100 and 115 teeth for the PTO-4R100). To remedy this simply drive the vehicle a short distance. Typically less than a mile will be sufficient to prepare the strategy to respond properly. Driving in first gear will speed this up. Driving stationary with the rear wheels off of the ground will not work. Also note that once the ignition is turned ON, CRANK, and START, sitting and idling for too long before driving may bypass the strategy's "search" cycle, leaving the driving remedy ineffective. If this occurs, shut off the engine and start the cycle over. No need to rush to drive, but avoid unnecessary delay.
I'm still digging for info.
Sorry for the delay in response (I have a 7 yr old with homework questions...)
Pressure has been checked before the PTO solenoid. The transmission is just not responding to the signal to increase pressure. The coast clutch has been checked and it is engaging, the transmission shop even replaced it's solenoid with no improvement. Do you have any thoughts as to why the transmission control indicator lamp (the overdrive light on the gear shift arm) goes out when the PTO is engaged? This lamp should come on instead. I " think " this is the problem.
Are you talking about the overdrive cancel light?
"Cannot find the PTO Circuit". The Super Duty F-Series PTO Circuit wiring changed soon after 1/1998 Job #1. The PTO Circuit wires moved more toward the driver's side, under the steering column and onto the harness for the black 4-pin APCM connector. The wires shown as 18-gage are 20-gage. Job #1 began with Circuit 640, red with yellow trace, 18-gage (really 20-gage), then changed to Circuit 295, light blue with pink trace, 20-gage. PTO Circuit 322, correctly remains light blue with yellow trace, but there is another wire with the same color near it (Circuit 323, not related to PTO). To verify that the correct wire is chosen, check to confirm that the 4R100 overdrive-cancel light is illuminated as it normally should be when the PTO Circuit is activated.
You should not be able to engage overdrive with the pto on. If you can then you have a wiring issue
I have read the PTO manual 3 times now. Best I can fiqure is that the port is tapped at the wrong place (see below for where it should be) or your wiring is wrong.
Thank you! You have given me something to work with. I just went out and ran the truck with the overdrive cancel light activated (lamp on) I engaged the PTO. The lamp went off (as it has been doing) but then I pushed the button and the lamp came back on.
I now need to check circuit 322 and 323 to confirm correct wiring. This may take a day or two since the hyd shop that did the install is in Reno and I live 30 miles from Reno. I would like to pay you for your help and stay in touch if future assistance is needed.