1998 Accord EX 4cyl manual trans. I have to "pump" the clutch in order for the starter to engage. Is this the 1)Clutch switch assembly or 2) clutch switch inhibitor?

Sorry no diagram. But here is how it works. In the start position(Power) the wire goes to the start fuse, from the fuse it goes to the clutch pedal switch. Push the pedal and it goes to the starter relay. On the other end is ground. If it is good it pulls the relay closed. On the closed end is battery power to the starter.

Not enough information to answer. Need manufacturer, year, model, engine size, 2WD/4WD/AWD, and Manual or Automatic transmission as applicable in order to answer the question.

Quick google search of those codes shows 1738 to be trans second clutch pressure switch issue, while 1739 is 3rd clutch pressure circuit issue. How long has it been since you changed trans fluid and filter? Might start there, but if many miles on car trans could be toast.

check the hydraulic clutch is releasing /engaging the clutch plate. Replace the clutch master cylinder if there is no clearance at the clutch slave cylinder piston rod. If cable clutch replace the cable as it is not allowing the clutch to engage.

Is everything hooked up at the battery and the main fuse box ?
Including the ground wires ?

Replace your main (fuel) relay. It's located under the dash behind the cruise control box.

I am sure it is self adjusting,it is a fluid clutch,no adjustment,the clutch assembly needs replacing.

A clutch issue youtend to have more of an engagement problem with 1st and reverse gear for a small time period before you notice other gears.You want to check the clutch hydrolic system for any leaks(clutch slave at transmission,clutch master,which you look for leakage on interior above clutch pedal)and at fluid resevoir.you also want to double check condition of trans fluid. strongly recommend using only HONDA BRAND MANUAL TRANS. FLUID when doing maintinance,fluid should be replaced every 30k on this car.The Honda brand fluid is like night and day on these cars,it WILL make a difference in shifting!!TRust Me on this point! Sorry now back to your main clutch issue,when driveing and you go to shift gears and normally notice grinding,with clutch pedal in shft out of gear and before engageing it into next gear do a double pump of clutch pedal then see if when continuing to next gear if it engagees smoother.if so you know you have without a dout a clutch pressure plate/disc problem. I can tell you that in twenty years the only manual transmissions themselves that ever had problems were due to outside influences(gear oil in transmission,improper driveing,etc.)let me know what you find and we can go from there..JOEL

You have an interlock switch on the top of the clutch pedal. Is it out of adjustment? This will prevent the starter from cranking.

Pretty good chance it's the clutch but check the clutch master cylinder and slave cylinder for leaks (also line between). A drastic change often is caused by failure of either component...generally if clutch fails, it is a gradual process (similar to how a brake pad wears)