just thought I might throw this in the ring. I have done extencive research on the EGR system and have found that if you keep your engine temp down it will never even come on. The EGR system is there too help bring combustion chamber temp down. normal operation is around 2500 degree's when it reaches 3500 degrees it opens and alows exhaust gasses to enter bringing the temp down. my EGR on my vet is not even hooked up and no light. have a 160 degree thermostat and a fan switch that turns the fan on at 200 degrees and off again at 180 degrees. and no problems or codes at all. by the way the reason my EGR is not connected is that when I purchased it I found that it was not connected and have found it very difficult to find the original control valve just like you have been discussing here. thought this might help.

The L98 does not 'diagnose' the EGR by opening the valve, and looking for a change in BLM as a result. (The way most GM OBDI EGR systems operate). It uses a temp switch. If the switch is detected closed upon engine start, or not closed when it should be (Appx 4 mins run time with no closed-throttle, temp >176ºF, no code 21,22,33, or 34 present) the light will light, and 32 will be set.


No one mentioned this switch. It's located at the base of the EGR valve on iron head engines, and on the EGR pipe on aluminum head L98's. I've had 3 of 3 L98 Code 32 occurrences be caused by this switch.

The switch hasn't been available for decades. But it can be "adjusted". On a cold switch, turn the wire connector CW until very slight resistance is felt. Or use a VOM to determine when the contacts are closed. Back off the connector slightly. About 15º or so. Put a daub of JB weld to hold the contact secure so it won't turn. That should do it. If you begin getting CEL's on start-up, and the Code is 32, the switch is too tight, and is staying closed. Loosen it up a bit.

EDIT: Never mind. I think I remember this thread. There isn't an EGR diagnostic temp switch on 90-91 L98.  The 85-89 L98 have the switch for diagnostics that is problematic.




|UPDATED|7/28/2012 4:26:38 PM (AZT)|/UPDATED|