1999 Freightliner Classic DDEC 4

Is there not a Separate Coolant Sensor in the Head for the Dash ?

 

Fld/classic is mechanical Gauge.

 

I was thinking they were ECM driven by DDEC 4. 25 year old memories aren't reliable

 

It’s a long shot, but being winter time, is it possible the dash selector is set on defroster during warm up? That will make the A/C compressor run, and fan switch to engage. I suspect 2 different problems. Only because the fan problem is very common. They come on for no reason, happened on my 99, and my 2000. Intermittently.

 

The Coolant Templ Sensor circuit, is on the engine side. Right rear of head. It has to have one. If it had a mechanical gauge, there would still be a temp sensor, and a sender to the gauge

 

edm box is bad in the center by the breakers

 

EDM box is available new from Freightliner. Replaced mine last year on a 98 FLD. Not expensive.

 

Fan control yes, gauge no. Unless specifically ordered. Now Century I think was. But not FLD cab.

It was a interface issue with cab technology. Your century's/columbia,t2000, the ugly Pete, Vn SlowVols different. A 379 Pete with ddec had 3 in thermostat housing. Ecm,dash gauge,dash light. 3 sensors, and one tied into ac/hi psi.


But always remember trucks of those years, especially FL would build anything you could pay for. So I can't claim this to be 100% true.

 

In the right rear of head, or thermostat housing. Ecm in right rear of head.

Also they most all have mechanical oil psi gauge. That logic brain in fuse box only controls indicator light bar in dash.