I have a 1999 F-150 w/ the 4.6L Engine. From what I have gathered I have the "Romeo" engine (VIN designation "W") installed in the truck. I have only had the truck for 4 days now and I was noticing two things -

1. A few seconds after starting the engine, there is a series of about 4 or 5 chimes repeated 4 times. I have been able to determine that either the "Service Engine Soon" light is burned out or broken.

2. The engine coolant temperature gauge on the instrument cluster always reads halfway between Hot and Cold. From the moment the key is turned (even if you don't start the engine) until it is turned off the gauge always reads the same. I assumed it to be a faulty coolant temperature sending unit, so I purchased one from the dealership (~ $11.00). When I went to replace the sending unit - I could not find the one on the engine. The Haynes manual says it is supposed to be on the "left front of the intake manifold", but there is nothing there but a metal plug. I can't even find the wires that connect to the sending unit. Is it possible that the sending unit is under/behind the alternator? I ask because I noticed two sets of wires going to something under there that I cannot see without removing the alternator.

I apologize for the long post, but if anyone could help me out, I would greatly appreciate it.

Thanks,
-J.T.

P.S. - I was able to connect a scanner to the truck to check for any codes and the only one I found was P1401 (DPFE Circuit High), so I have already replaced the DPFE sensor.

 

Hi and welcome to the forum.


It is on the top front of the drivers side cylinder head .
Jimmy

 

LxMan1,

The only sensor that I found on the driver's side cylinder head is the camshaft position sensor directly under the coil pack. The only other item I found on the driver's side of the engine is the thermostat housing on the front edge of the intake mainfold.

I do have two holes in the intake manifold on the passenger side, but both are capped off. I though that maybe one of these holes was for the coolant temperature sending unit, but I cannot find and electrical connections hanging loose in that area...

I've reviewed the Haynes manual several times as well as having tried to trace all the electrical connection around the front of the engine, on both driver and passenger sides, without any success at this point...

 

You will need to remove the alternator to get at it. Its kind of under the intake. I have a wrench bent just for that sensor.

 

I was going by the picture from the Ford service manual. The alternator wasn't in the picture that I looked at so Dave is correct.
Jimmy

 

Lx1Man & bosshoss,

That you gentlemen very much. I suspected that it might be under there, but I wanted to make sure before I started pulling everything off to find out. It has been a little concerning to say the least to realize that the coolant temperature gauge is not working properly while I am driving around town.

Hopefully, I will have enough time tonight to tear it down and replace the sending unit.

Thanks!
-J.T.

 

Good luck, it's probably not as bad as it looks.

Jimmy

 

Well I got the alternator out of the way and went to change the sending unit this evening only to find out that the connector and the part that I received from the dealership do not match. It is too late to call the parts department and have them double check the part, so it will have to wait until tomorrow.

Just as a sanity check, can anyone who has a 99 F-150 with the 4.6L V8, check to see if they have anything mounted on the passenger side of the intake manifold (directly on the top front portion left of the alternator). If you have two bolts/caps there (possibly with dark red thread sealer around the threads going into the manifold), please let me know one way or the other.

Thanks,
-J.T.