engine & abs lights on -HELP PLEASE-

i have a 93 astrovan 4.3. the abs light and the service engine soon light go on and off intermittently. i have the code reader and it tells me that the ecm code is

"#43 electronic spark timing (EST) circuit - low voltage detected / electronic spark control (ESC)- circuit problems".

and the abs fault is

"#8 shorted dump valve circuit or faulty ecu".

both these lights started coming on within a day of each other...i kinda sounds like maybe something is not putting out enough voltage or something.
any ideas what it could be??...
thanks

nm