1999 F355 GTB OVERHEATING!!

First question: Yes

Second question: Yes

Third question: No

 

That is what I am talking about. I have replaced many for a non op fan and they never set a CEL.

 

Understood, thanks Brian for the clarification.

 

Yes.

 

No. Note it says "transmitter" not "sensor"....the #148677 is used for the water temp gauge on your dash.

BTW, have you pulled the fuse panel in the passenger footwell and inspected it for melted plastic or bad contacts yet? You need to look at the back side of it for damage.

 

Jeez...I've been watchiung this one from afar...
I would concur with all that RifleDdriver , etc has offered you...but the last quip as to grasping for straws seems to indicate your own acknowledgement that oit is now time fro some real grunt work....

In 129 cars, theere is the real and truly the case issue of amp pin connector failures within the harnesses and boot heads....
Rifledriver has an SD-1-I do believe- so proximity to him and a time and materials bill is the likely resolution to, ultimately, performing a wire by wire, and pin to pin proofing of the harness, sensors, ECUs, etc to the channel affected.

A shop with the pin boxes, and the layovers, is also a very useful shop for this...but it is TIME consuming..which means costly....I once spent 3 weeks chasing down 1 AMP pin for the suspension in a harness/boot head which was the culprit, only to find that the harnesses were NLA, and , you'll really die hearing this-AMP had not made those pins in years, and we needed to chase down last known buyer in Belgium(he offered to give me several hundred as a sample, as his minimum order had been 17, 000 pins!...True story....

The moral of the story is that this is emminently fixable, just not likely easily, nor likely quickly.
The key is competence in either your own diagnostics skill sets, or those of your sevice facility's.
good luck, plese let us know what is the final solution...

 

Before changing the sensor, have the car plugged to a SDx, or a cheap OBD2 reader. It will show you what the Motronic is considering for the coolant tempearture, in real time, even during driving. It will then be easy to check if the temperature is consistent with the coolant temp gauge.

If yes, no need to change the sensor, your problem is between the motronic output (including the Motronic itself) and the fan i.e. wire between motronic and relay including the intermediate 14 pins connector, relay, fuse, wires between relay and fan. Is the relay commanded by the Motronic when the temp is high (can you ear a "click" if you remove and re-install the relay)? Does the fan blow air when you by-pass the relay with a short piece of wire? You can quite easily isolate the arear of concern.

If no, changing the sensor wont ensure you are OK after that. You have first to check that the wires between the Motronic and the sensor are OK. With key in position II, unplug the sensor and check that you have some voltage between pins and ground (# +5V).

 

Was the car fixed? If so what turned out to be the problem?