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Pampered-Z · 12-29-2008, 01:17 PM

Be very careful trying to jump the fans! They are turned on by the ECM grounding the circuit! If you add power or feed power back into the grounded side you can fry parts, even the ECM!

There is also a way to ground the relays (manual fan switch mod), but I'm not 100% sure on the 96-97 wiring as its different them my 93. So I can't tell you the proper way.

The two fans work independent. Fan1 (primary) comes on at 221 degrees, fan 2 @ 235 degrees. Both fans are controlled thru the ECM. I think on the 96-97s each fan has its own relay, I believe the 3rd is the AC fan on relay.

The most common type of failure is with the sensor that gives the temp to the ECM. It is located in the front of the water pump housing on the right side down below the small inlet (It is a bit of a PITA to get to.). The dash gauge is operated off a completely different circuit and by the sensor in the driver's side head. So the reading on your dash does not mean the ECM has the same temp reading, since neither fan is working its most likely not a relay, I'd lean more towards the sensor.

Couple things you can try before buying parts:

1) There should be two fuses and relays in the box under the hood. The relay for the fog lamps is the same as the fans, try swapping that, see if the lights still work, or a fan comes on.

2) The ECM uses the coolant temp for fuel tables. If you noticed the car is running very rich, that might be another reason to look at the sensor as to why you're having this issue.

All else fails, have someone with a scanner see if the ECM coolant temp matches or at least is close to what the gauge on your dash is reading.

3) Never tried this myself on an OBDII car? So maybe someone else with a 96-97 could do it and verify it works??? With the key on, but the engine not running jump the #5+6 pins on the ADL, this should put the ECM is FTM ( Field test mode - form of Limp Home Mode), causing the check engine light to come on and the fans should come on. If the fans do come on, it's probably the sensor. If they don't them you may have a bigger issue. Time to break out a volt meter and testing wires from the ECM to the relays.

12-29-2008, 01:17 PM	#12
Pampered-Z Sliderule / Moderator Join Date: Oct 2004 Location: Catawissa PA Posts: 2,294 iTrader: (1)	Be very careful trying to jump the fans! They are turned on by the ECM grounding the circuit! If you add power or feed power back into the grounded side you can fry parts, even the ECM! There is also a way to ground the relays (manual fan switch mod), but I'm not 100% sure on the 96-97 wiring as its different them my 93. So I can't tell you the proper way. The two fans work independent. Fan1 (primary) comes on at 221 degrees, fan 2 @ 235 degrees. Both fans are controlled thru the ECM. I think on the 96-97s each fan has its own relay, I believe the 3rd is the AC fan on relay. The most common type of failure is with the sensor that gives the temp to the ECM. It is located in the front of the water pump housing on the right side down below the small inlet (It is a bit of a PITA to get to.). The dash gauge is operated off a completely different circuit and by the sensor in the driver's side head. So the reading on your dash does not mean the ECM has the same temp reading, since neither fan is working its most likely not a relay, I'd lean more towards the sensor. Couple things you can try before buying parts: 1) There should be two fuses and relays in the box under the hood. The relay for the fog lamps is the same as the fans, try swapping that, see if the lights still work, or a fan comes on. 2) The ECM uses the coolant temp for fuel tables. If you noticed the car is running very rich, that might be another reason to look at the sensor as to why you're having this issue. All else fails, have someone with a scanner see if the ECM coolant temp matches or at least is close to what the gauge on your dash is reading. 3) Never tried this myself on an OBDII car? So maybe someone else with a 96-97 could do it and verify it works??? With the key on, but the engine not running jump the #5+6 pins on the ADL, this should put the ECM is FTM ( Field test mode - form of Limp Home Mode), causing the check engine light to come on and the fans should come on. If the fans do come on, it's probably the sensor. If they don't them you may have a bigger issue. Time to break out a volt meter and testing wires from the ECM to the relays. __________________ 93Z M6 Black: The 385 Lives! Supercharged, 3-core front mount intercooler, GTP heads, 3:73's, Street twin clutch, Jethot Longtubes, Mufflex 4" catback/spintech, S+W cage, Spohn Suspenion, Yada Yada Yada 1) Build it 2) Race it 3) Break it 4) Repeat!!! Last edited by Pampered-Z; 12-29-2008 at 01:18 PM. Reason: Speeling, what else!