5R110W P0742: TCC Stuck On Causes & Fix

Most P0742 write-ups online describe the code as "torque converter clutch stuck on" and send you looking for a sticking lockup valve. On a Ford 5R110W TorqShift that description is not how Ford sets it. On this transmission P0742 is an electrical code: the PCM has found the TCC solenoid control circuit shorted to ground. A converter clutch that mechanically refuses to release has its own code, and it is not this one. If you mix the two up, you end up pulling a solenoid body or a converter to fix what is really a pinched wire or a fuel-soaked connector.

This post covers how Ford's monitor decides to set P0742 on the 5R110W, why a short to ground on that circuit can leave the converter clutch applied, the pin-by-pin checks that find the fault, and what to replace once you have found it. Specs come from the ATSG TorqShift manual, Ford's OBD system operation summary, Transmission Digest, Sonnax and Ford fluid data, all listed under Sources. If the truck is setting the slip code instead, see our 5R110W P0741 guide.

Recommended 5R110W parts

Parts that fix the causes of P0742 covered below: the internal harness when the short is inside the case, the TCC solenoid when its coil is shorted, and the full solenoid set for a high-mileage solenoid body.

5R110W Internal Wiring Harness 2003-2010

$137.99View part

5R110W Tcc Solenoid 2003

$65.68View part

5R110W Transmission Solenoid Kit, 3C3Z-7G383AB

$180.99View part

What P0742 means on this unit

The ATSG 5R110W diagnostic code chart lists P0742 as "TCC Solenoid circuit, shorted to ground." Ford's own OBD system operation summary uses the same three electrical TCC codes across its step-ratio transmissions: P0740 open, P0742 short to ground, P0744 short to power. The solenoid's output driver checks them continuously. Ford's stated threshold is the driver's feedback circuit not matching the commanded driver state for 0.5 to 5.0 seconds. All three are MIL codes.

The functional TCC faults are separate. Per the same Ford summary, P0741 is the stuck-off code (slip above 100 rpm for 3 seconds after each of 3 lock events), and P2758 is the stuck-on code: slip across the converter under 20 rpm with the converter commanded off, in at least 3 different gears. Ford makes P2758 non-MIL. Its reasoning is that a stuck-on TCC can cause driveability complaints and engine stalls but does not affect emissions or fuel economy. So if a customer says "it stalls when I stop" and there is no P0742 in memory, check for a pending or non-MIL P2758 and a sticking valve. If P0742 is there, start with the wiring.

One honest caveat: Ford calibrations changed over the years this unit was in production. The ATSG chart and the Ford summary agree on P0742, but read the code description your scan tool shows for that VIN before you commit to a path.

How the TCC circuit is wired

You need the circuit layout to find a short, so here it is. Per ATSG, the TCC solenoid is one of seven variable force solenoids on the solenoid body under the pan. It is directly proportional: the PCM varies current from 0 to 1 amp, and 1 amp equals maximum converter clutch apply pressure. Sonnax's solenoid identification chart lists it the same way. The PCM controls it on the ground side.

Now think about what "shorted to ground" does on a ground-side driver. The wire from case pin 8 back to PCM pin 14 is the solenoid's ground path. The PCM normally pulses it to set current. If that wire rubs through to the frame, or the internal harness shorts to the case, the solenoid gets a hard ground the PCM cannot switch off. The coil then sees full system voltage whenever VPWR is present. With 12 V across a coil of roughly 4.4 ohms, current runs well past the 1 amp control range. On a directly proportional solenoid that means maximum apply pressure. That is the electrical way to get a converter clutch that will not release, and why P0742 shows up with the same stall-at-a-stop complaint as the mechanical stuck-on code. A short to ground inside the PCM's driver produces the same result.

Because pin 7 feeds both TCC and PC-A, a fault on the power side tends to show up as a mix of TCC and line pressure codes, not P0742 alone. A clean, single P0742 points you at the pin 8 / pin 14 side.

Symptoms you will actually see

• Engine stalls or nearly stalls coming to a stop, or lugs hard as the truck slows, because the converter is still locked when output speed drops.
• Stall or heavy bump when shifting into Drive or Reverse with the engine idling, if the short is present at key-on.
• Check engine light with P0742, often intermittent at first, setting over bumps or after the truck has been washed or driven in rain if the short is at a chafe point or connector.
• No symptom at all when the short is intermittent and not present at a stop. Many P0742s come in as a code-only complaint.

Diagnosis: find the short, do not guess at it

Step 1: scan data and freeze frame

Record freeze frame before you clear anything. Note whether the code set at idle or at speed, and fluid temperature. Then watch commanded TCC (pressure or current, depending on your tool) against engine rpm and turbine shaft speed (TSS) with the engine idling in Park. With TCC commanded off, engine and TSS should not be locked together at a stop. If the converter is applied at idle while the PCM is commanding zero, the solenoid is being grounded outside the PCM's control, or the PCM driver itself has failed shorted.

Step 2: resistance at the case connector

Key off. Disconnect the transmission case connector. On the transmission side, measure pins 7 to 8. ATSG specifies 4.1-4.7 ohms at 72 degrees F. A reading well under that points at shorted turns in the coil. Then measure pin 8 to the transmission case. It should be open, effectively infinite. Any continuity there means the TCC ground circuit is touching the case somewhere inside: the internal harness or the solenoid itself. Do the same pin 7 to case check, since a power-side short to case will usually take out other codes too.

Step 3: the vehicle harness

With the case connector still unplugged, disconnect PCM connector "B". Check PCM pin 14 (Brown/Orange) to chassis ground. It should be open. Then check continuity from PCM pin 14 to the harness side of case pin 8; it should be close to zero ohms. A wire that reads open between the two ends is a P0740 problem, not P0742. A wire that reads to ground is your fault. Trace it along the frame rail and wherever it passes brackets or the exhaust. Flex the harness while you watch the meter, because intermittent P0742s are almost always a chafe that only touches with movement.

Step 4: the PCM connector on the 6.0L

On 2003-2007 6.0L trucks, look hard at the PCM connectors before you condemn anything else. Wayne Colonna documented a 2005 F-350 6.0L in Transmission Digest where diesel from a leaking water-in-fuel sensor ran down the C138E harness, wicked through the connector and left about a pint of fuel inside the PCM on the driver-side inner fender. That truck stored pressure control solenoid codes (P0753, then P0752 and P0973), not P0742, but it is the same family of failure: solenoid driver circuits reading shorts that are not in the transmission. The fix was a new PCM and a new water-in-fuel sensor (6C3Z-9C264-A), with the harness and connector cleaned and reused. If you open the connector and smell fuel, stop chasing the solenoid.

Step 5: inside the pan

If pin 8 reads to case with the vehicle harness ruled out, drop the pan. Inspect the internal harness where it runs to the solenoid body and anywhere it can be pinched by the pan, a bracket or the solenoid body itself, especially if the pan or solenoid body has been off before. Unplug the TCC solenoid and re-measure from the case connector: if pin 8 to case now reads open, the solenoid is shorted to its own housing; if it still reads to case, the harness is the fault.

The fix

• Chafed vehicle harness: repair the wire with a soldered, heat-shrunk splice, and re-route or re-clip it so it cannot rub again. Clear codes and re-check pin 14 to ground.
• Internal harness shorted: replace the internal harness. It is cheap next to a second pan drop. Torque the solenoid body bolts to 10 N-m (89 in-lb) per ATSG; they thread into aluminum.
• TCC solenoid shorted: replace the solenoid. On a high-mileage unit where the other six solenoids are original, a full set is the better buy because the solenoid body is already out.
• PCM driver failed shorted: replace or reprogram the PCM as required, and on a 6.0L, fix whatever let fuel or water into the connector first.
• Refill: Ford's Motorcraft chart authorizes MERCON LV for the 5R110 TorqShift, including back-service. The 2009 Super Duty owner guide lists about 17.5 qt (16.6 L) including the cooler. A pan drop on its own takes much less; set the final level hot on the dipstick.

After the repair, clear codes and verify with the same scan graph: TCC commanded off at idle in gear, engine and TSS not locked together, and lockup applying and releasing normally on a road test. If the converter now applies normally but slips, you are into a P0741 or P1744 problem. Colonna's 5R110W no-lockup article walks through the plugged 0.018-0.021 in. solenoid feed orifice, stator tube seal and valve retainer causes for that.

Preventing a repeat

Repeat P0742s almost always come from a repair that fixed the wire but not the reason it shorted. Clip the harness away from anything that moves or gets hot, and route it the way Ford did before someone else re-routed it. Any time the pan or solenoid body comes off, check that the internal harness is seated in its retainers before the pan goes back on. On the 6.0L, keep the water-in-fuel sensor and separator dry and serviced, because fuel in the PCM connector will take out more than one circuit.

Need parts for this job?

Our 5R110 parts page has internal harnesses, the TCC solenoid, full solenoid kits, valve bodies and rebuild kits for the TorqShift, all on our own checkout.

FAQ

What does P0742 mean on a Ford 5R110W?

On the 5R110W, P0742 means the PCM found the torque converter clutch solenoid circuit shorted to ground. Both the ATSG 5R110W code chart and Ford's OBD system operation summary define it that way. It is an electrical code, not the mechanical stuck-on code, which Ford sets as P2758.

Can P0742 make my truck stall at a stop?

Yes. The PCM controls the TCC solenoid on its ground side, so a short to ground can energize the solenoid with no way for the PCM to turn it off. The solenoid is directly proportional, so full current means full apply pressure, and a converter that stays locked as the truck slows can drag the engine down to a stall.

Should I replace the TCC solenoid for P0742?

Not until you have measured it. Check 4.1-4.7 ohms across case connector pins 7 and 8, then check pin 8 to the case and PCM pin 14 to chassis ground. A chafed harness, a shorted internal harness or a fuel-soaked PCM connector can set the same code with a good solenoid.

What is the difference between P0742 and P2758?

P0742 is the electrical short-to-ground code and turns on the check engine light. P2758 is Ford's functional stuck-on code, set when converter slip stays under 20 rpm with the TCC commanded off in at least 3 gears. Ford makes P2758 non-MIL, so a mechanically stuck TCC valve can cause stalling without a lit MIL.

Related guides

• 5R110W P0741: TCC Stuck Off Causes & Fix
• 5R110W TCC Lockup Explained
• 5R110W Torque Converter Shudder
• 5R110 Shift Solenoid Symptoms
• 5R110W Limp Mode Causes