1984-1989 Corvette Delay Timer Board Testing. (Our board)

You purchased a new board and it only lasted for (insert time here).  There is a reason why and in almost all cases the issue is in the car.   We designed our reproduction board to fail if there is any issue in the car and I’ll explain.

There is a fuse our board… if you blow it it’s easy to check if you have a multi meter, but if you blew the fuse there is an issue with the car. To test the board, check continuity with a multi-meter from B to C, it’s that simple!  If the fuse is good you’ll have continuity, if the fuse is blow you won’t.

If you blew the Mosfet… (Mosfet is the larger square item to the left of the green fuse in the top picture and above the fuse in the lower picture) in the picture below. If this is burned you’ve cooked it and you have a really bad issue, I’ll elaborate below.

We updated the board design when we initially started reproducing the boards. We did this so that if the car has any issue it will blow the fuse and not damage the car or board and thus preventing any other damage from being done to the car. Typically if there is a problem that took out the original board the problem is still there! Lets face it, the boards are not a band-aide and so simply replacing the board without fixing the issue only causes the same issue… a board blown! This is exactly  why we fused the board and to repair a blown fuse requires you to send us the board for repair, the charge is 14.00 plus shipping.  This seemed like a better solution than you replacing boards over and over spending needless money.

There have been reports of timers showing harsh burns or disintegration from heat and this is not due to a flaw in the timer board.  If you removed your old board and the box or old board looks melted or burned, you have a different issue and do not install a new timer board until this issue is repaired.

The flaw that causes this issue can be found in the car in the form of a failed rectifier attached to the either the rear hatch release solenoid or the deck lid release solenoid. All instances reported are directly related to the Coupe and Convertible cars and is caused by a malfunction in the rectifier which is there to stop a voltage spike.  The rectifier is used for the suppression of the voltage spike created by the rear hatch/deck lid release solenoid is activated and released.

The timer has to be in sequence with the rear hatch switch and to the deck lid release switch to prevent opening of both while the car is in motion.  When the rectifier fails to stop the voltage, the voltage spikes the board and causes what is termed “thermal runaway”, the Mosfet over heats and the melting starts.  A schematic has been posted on our website to help you understand the issue at this link.

http://repairs.willcoxcorvette.com/corvette-delay-lamp-timer-and-switch-schematic-1986/  <- updated link 08-11-2015

Now if the mosfet on the new board is cooked, (Mosfet is the larger square item to the left of the green fuse in the top picture and above the fuse in the lower picture), you’ll need another board more than likely but the only way to know for sure is the send us the board for examination. In 2015 we updated the Mosfet to a IRF540n which is capable of taking 1000 volt spike, but even with this upgrade, the limit’s can be exceeded if the rectifier in the rear circuit is not working.



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