Batboard

Has any found a way to eliminate the noise coming from the ECM on the 1988-95 chevy pickups.It has been a problem for me and others.seems to be coming from the roof mounted, in the center of the cab, lowband antenna.as soon as engine is turned off it usually takes 10 to 20 seconds for the noise to dissapate.

chad wrote:Has any found a way to eliminate the noise coming from the ECM on the 1988-95 chevy pickups.It has been a problem for me and others.seems to be coming from the roof mounted, in the center of the cab, lowband antenna.as soon as engine is turned off it usually takes 10 to 20 seconds for the noise to dissapate.

Had this problem with a 91 Chevy Blazer, found the RFI (found it using a spectrum analyzer) to be coming from the "speed module" which was located behind the passenger kick panel.

Contacted the dealer who put me through the district sales manager and got me a replacement module - took 5 minutes to replace and problem went away.

My low band radio was at 49Mhz.

Bill

On the 88-96 Chevy/GMCs, there is a fuekl pump timer module which is behind the glove box. This timer makes the fuel pump run for approx. 30 seconds after the engine is shut off to avoid a vapor condition in the throttle body area. This timer is usually on the heavier trucks such as the 3/4 and 1 tons. It's a black plastic box and is on the underside of the crossmember under the glovebox hinge. It's accessed by removing the glovebox/hinge assembly and going in through the opening where the glovebox was. You can simply eliminate this module and it doesn't affect a damn thing. It's not even on all trucks.....that is if this is where the noise is coming from. The fuel pumps have a capacitor inside of them to eliminate noise and this module seems to help transmit this noise on AM radio and other radios. If you have an aftermarket replacement fuel pump, it may not have the EMI cap. installed to it causing more noise yet.

I had an "asstinko" (alinco) ham rig that had 6m in it and my 90 blazer hammered the hell out of that thing, I ended up doing the same thing as the above post mentioned, but I had the aftermarket fuel pump was causing the problem. Interesting side not the kenwood tk-630 was able to reject this and did not deminsh performance. Since then I am driving a new vehical but thougth I would put my 2 cents in!

Thanks you both for the info.I am going to try that now!

Ahh i had the same Problem with my 89 s10 Not with the 6m mitrek but with my high band radio. i just used pl and i get ride of it, but it is speed cencor as well