FM Interference when key is at ''ON''

[DomGSR-T]

Hi!

I have been having issues for a while from the FM radio on my 98 Integra. Works very very good when key is at ACC, but when I switch to ON I get bad interference on hard to get stations... I search by removing fuses and found that the fuse 13 Fuel Pump (SRS UNIT) was causing the problem, search deeper and fond Fuse 44 - (FI E/M 15amp PGM-FI main relay) that is on the same circuit is also causing problem, as soon as I remove that fuse it's perfect.

I tried to disconnect the injectors, disconnect the external coil, shut the fuel pump OFF, disconnect the IACV and those tests did nothing. Last thing on that circuit is the ECU, Disconnected connector, ''D'' nothing happening, Same for connector ''C'', but when I disconnected the connector ''A'' it was perfect... Something on the connector A is causing me trouble... I made sure all the important grounds are good with metal to metal contact

Any inputs on what could be my problem?

Thanks in advance!

[Spunkster]

Are you using resistor or non-resistor spark plugs?

[DomGSR-T]

Oh I also test to remove all the spark plug wires... same results and I'm using BKR7E

[Spunkster]

Could just be poor reception from the antenna as it is as old as the vehicle.

[DomGSR-T]

Could just be poor reception from the antenna as it is as old as the vehicle.

Well it works perfect when key is on ACC only at ON or when engine is running that I have this problem and Radio and antenna are new of the year... problem was there before the change of antenna and radio

[DomGSR-T]

would it be a good idea to buy a cheap obd1 jumper harness and do some testing? like cutting one wire at a time until I find the bad circuit?

[kraquepype]

I had the same issue, and still do unfortunately. (I saw your PM about this, thought I would just reply in thread)

Changing to a different radio helped a bit, but lately I only listen to local stations or cassettes on mine. There is still a noticeable change in reception when the ECU is receiving power.

I have suspected it is the bluetooth module, but I haven't isolated it by removing the S300 module yet. That is something to try.

Are you using an OBD adapter harness for your ECU? I am using a Monotech harness.

[DomGSR-T]

Yes i'm using a harness adapter don't remember the brand. I have bought a ''EMF Protection Fabric'' to completely cover the ecu and it does not change anything, waiting for the other harness to do more testing

And yes removing the s300 module would be a good test too!

[DomGSR-T]

here's an update, looks like I found the problem, it's coming from the analog input wires of the S300, As soon as I disconnect the radio is fine... and when I touch the unplugged wire side the interference comes back even stronger :S

Any ideas on what it could be?

I have attached the movie/audio of my issue