Joseph Andres

iTrader: (6)

I have a 1988 GTA 5.7L TPI Automatic. I am going to purchase a new computer for it because i believe there is a bad ground in it for one of the cooling fans. The secondary fan always comes on with the ignition. I have already checked the fan motor, the relay, the A/C low pressure switch and the wiring. Everything is OK. I replaced the low pressure switch and the relay with new ones, the problem is still there. The only thing left is the computer. I have talked to other people about this. I came across a Corvette owner that had the same problem and he said that he replaced the computer (nothing else) and the problem ceased. He bought the computer from Auto Zone for about $80. I was thinking of purchasing the same one from that store but for my particular vehicle. I just wanted to check and see if there were any better types of computers to look for. Are there any particular differences in which type of computer to choose from or are they all basically the same?

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1988 GTA 5.7L Auto
355 ci. block, SLP Cold Air Intake w/ K&N, fully modified MAF Sensor, TPIS 52mm Throttle Body w/Air Foil, Throttle Body Bypass Hose, Fully Ported and Polished Plenum, Nikel-plated Ported SLP Siamesed Runners, Ported TPIS Big Mouth Intake Manifold, stock heads w/ 1.52 Comp Cams Self-aligning Roller Rockers, TPIS ZZ-9 Roller Camshaft, TPIS Valve Springs, Cloyes True Double Roller Timing Chain, TPIS Adjustable Fuel Pressure Regulator, Balanced Bosch 22 lb/hr Fuel Injectors, MSD 6AL, Taylor 10mm Wires, Bosch Platinum +4 Spark Plugs, MSD Blaster Coil, March Underdrive Pulleys, 6 3/4" Vibratech Streetdamper, TPIS Level 3 PROM, 160 T-stat, Low Temp. Fan Switch, Stock Distributor w/ Bronze Gear, SLP 1 3/4" Headers, Random Technologies High Flow Cat., Adjustable Borla Cat Back Exhaust, Level 10 PTS-3 700R4 Trans, B&M Holeshot 2400 Stall Converter, B&M Trans Cooler, TCI Aluminum Finned Trans Pan, Torque Converter Lock Up Switch, 3" Balanced Aluminum Driveshaft, 3.73 Richmond Gears, Auburn Pro-Series Differential, LPE Aluminum Differential Cover w/ Main Cap Preloads, BF Goodrich Drag Radials, Hotchkis Lower Control Arms, Hotchkis Panhard Rod, Hotchkis Tie Rod Adjuster Sleeves, Bilstein Heavy Duty Shocks and Struts, 1LE Springs, Energy Suspension Polyeurethane Bushings, Global West Tubular Subframe Connectors, Global West Steering Box Brace, HP Motorsports 3 Point Strut Tower Brace

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

Blade

Well as far as stock replacement there's only two options pretty much. The stock GM type ECM or an aftermarket ECM like Howell programmable ECM. If you just want to fix your fan problem, I'd stick with a stock ECM. The howell is about 700-800 dollars, and it's a helluva lot cheaper to burn chips for your stock GM ECM Hehe

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92 Z28 L98 350
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Ported stock heads, XR270HR-10 cam, TES headers, Crane AFPR, Flowmaster catback, MSD ignition components.
Best ET 13.5@105 mph
"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)
Click here to see my car at Truspeed.org

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Joseph Andres

iTrader: (6)

I just installed the new computer from Auto Zone and found out that it is not the problem. What else can i check for? It's not the motor, not the low pressure switch, and not the ECC. I'm completely lost on this one.

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1988 GTA 5.7L Auto
355 ci. block, SLP Cold Air Intake w/ K&N, fully modified MAF Sensor, TPIS 52mm Throttle Body w/Air Foil, Throttle Body Bypass Hose, Fully Ported and Polished Plenum, Nikel-plated Ported SLP Siamesed Runners, Ported TPIS Big Mouth Intake Manifold, stock heads w/ 1.52 Comp Cams Self-aligning Roller Rockers, TPIS ZZ-9 Roller Camshaft, TPIS Valve Springs, Cloyes True Double Roller Timing Chain, TPIS Adjustable Fuel Pressure Regulator, Balanced Bosch 22 lb/hr Fuel Injectors, MSD 6AL, Taylor 10mm Wires, Bosch Platinum +4 Spark Plugs, MSD Blaster Coil, March Underdrive Pulleys, 6 3/4" Vibratech Streetdamper, TPIS Level 3 PROM, 160 T-stat, Low Temp. Fan Switch, Stock Distributor w/ Bronze Gear, SLP 1 3/4" Headers, Random Technologies High Flow Cat., Adjustable Borla Cat Back Exhaust, Level 10 PTS-3 700R4 Trans, B&M Holeshot 2400 Stall Converter, B&M Trans Cooler, TCI Aluminum Finned Trans Pan, Torque Converter Lock Up Switch, 3" Balanced Aluminum Driveshaft, 3.73 Richmond Gears, Auburn Pro-Series Differential, LPE Aluminum Differential Cover w/ Main Cap Preloads, BF Goodrich Drag Radials, Hotchkis Lower Control Arms, Hotchkis Panhard Rod, Hotchkis Tie Rod Adjuster Sleeves, Bilstein Heavy Duty Shocks and Struts, 1LE Springs, Energy Suspension Polyeurethane Bushings, Global West Tubular Subframe Connectors, Global West Steering Box Brace, HP Motorsports 3 Point Strut Tower Brace

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

Grim Reaper

I suggest it is your wiring somewhere between the ecm and the fan or fan relay.

The ecm needs a variety of conditions for it to trigger the second fan; including the temperature to be 151*C. I say there is a short since you have replaced the pressure switch and the relay. I suspect this also happens whether the a/c is on or off.

I am actually looking at this, but from a reverse situation; where I can control the second fan WITHOUT the A/C on and the low pressure switch. Just the temperature set in the the eprom.

87Z-ya

iTrader: (1)

Its the sensor in the pass side head. More than likely this is the problem. Its sending a reading of the engine being hot and turning the fan on. The only thing that sensor controls is the secondary fan. Good luck, sorry you bought a ecm for nothing.

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87z 383,afr 190's, crane hyd roller(224/230-.509/.528,112 sep),Ported and polished mini ram, 30lb inj, 3.42 gears, strange 12 bolt, tremec 5spd, , 1,3/4" slp headers.

Grim Reaper

Yes 87, but the A/C must also be on to cause this condition and he stated that he replaced the low pressure switch too. That is why I lean to the wiring, probably shorting on the the relay as even if the low pressure switch was shorted and A/C was on, he still wouldn't hit the 151*C requirement of the eprom.

PROCHARGED89Z

If a certain wire is grounded out in the relay harness it will do this.Try this inexpensive experiment.Just switch the wiring from one fan to the other see if it is the wires them selves which are bad.You dont need to replace the switch on the side of the pass head to check operation,if you have continuity from the switch to the head when the car is sitting the switch is bad.Its in the wiring or the fan itself,just switch one hookup to th other to see what happens