Cooling system

112652

MEMBER
1999 CADILLAC ELDORADO
V8
FWD
AUTOMATIC
130,000 MILES

I have a 1999 Cadillac Eldorado with a cooling problem. The cooling fans do not operate, checked fuse, is still good. Looking through the shop manual they reference throttle body circuit flow. Is this associated with the cooling system or electrical system, would you explain.
thank you
Ron

1 Reply

FACTORYJACK

MECHANIC
4,159 POSTS

It should be describing coolant flow to the throttle body, basically for throttle body heating to prevent cold weather icing. You didn't mention it, but I have to assume it is overheating. Did you read the coolant fans description in your service manual, and know the modes of operation? Many requesting advice assume a cooling fan fault, and more often than not, it is not knowing the operation charatceristics. In all aspects, the fans should be coming on when A/C is requested, and that could be at low speed. I will include the operation literature, reply to post with any questions.

Electric Cooling Fan System

Circuit Description

To determine if a fault is present perform the Cooling Fan Functional Check.
See: Powertrain Management Computers and Control Systems Testing and Inspection Component Tests and General Diagnostics
If DTC P1660 is set, or sets during the functional check, it must be diagnosed before proceeding with any of the symptom tables. When the PCM commands low speed fan operation it grounds Cooling Fan Relay 1 which allows current to flow through both cooling fans in a series circuit to ground. If the PCM commands high speed fan operation it grounds all the cooling fan relays, including Fan Relay 1, which changes the circuit to a parallel circuit to ground. If a fault occurs certain symptoms will occur due to the series/parallel circuit design.

The PCM will command fan operation when:

Low Speed Fan Operation
Engine coolant temperature exceeds approximately 106°C (229°F).
Transmission fluid temperature exceeds 150°C (302°F).
A/C operation is requested.
After the vehicle is shut OFF if the coolant temperature at key-off is more than 151°C (304°F) and system voltage was more than 12 volts. The fans will stay ON for approximately 3 minutes.
The fans will switch from low to OFF when the coolant drops below 102°C (216°F).

High Speed Fan Operation
Engine coolant temperature reaches 112°C (234°F).
Transmission temperature is more than 151°C (304°F).
When certain DTCs set.
The fans will switch from high to low (except DTCs set) when the coolant drops below 106°C (229°F).