Astrovan Electrical Issue

Hello All,
I am new to any kind of forum website and I am desparate for answers on a electrical problem. I have a 2001 Astrovan and when you first start it there is a erratic electrical short ocurring. Lights dim and brighten, engine r's flux in time ,blower motors too. You can watch the amp gauge flux in time also as if someone is randomly shorting across the battery. The problem seems to clear as the car warms up but if you wind the engine to a high RPM,the voltage gauge fluxuates once again. Changed the aternator twice and new battery on the second alternator change. Cleaned and reconnected all visiable battery and ground connections. Spent many hours shaking wires and connections and checking fuses! Is this a component failure?
Any sugguestions beside a FOR SALE sign. Vehicle has been great to me until nowand cant afford to get another car right now

Thank You!!

Welcome Aboard!

There are a few easy, but critical items to check.

First, the main auxiliary power stud on the front of the underhood electrical center should be checked for clean and tight cables. The stud connects the main power buss to the battery/vehicle power, so the lower (buss) connection should also be inspected.

Second, the main body power fuses in the electrical center should be checked for clean connections. These are the large 60A (and maybe 80A) Maxi fuses. The blades can become corroded and cause resistive connections.

Next, the battery power and ground cables need to be checked, not only for clean and tight connections at both ends as you already have, but for damage along the cables' lengths.

Also, the smaller electrical connector at the alternator itself should be checked. This is the alternator regulator's Load, or "L" terminal. This terminal is connected to the PCM to regulate when the alternator is allowed to charge. If the connection between the PCM and alternator L terminal is not intact. the alternator will not output voltage. If that circuit is intermittent, the symptoms you describe can occur.

Finally, if you have access to a bi-directional scanner, you can both monitor AND command the PCM output to the alternator L terminal via the scanner. This may provide a good indication of whether the problem is on the charging side or load side of the system. If turning off the L terminal output stops the voltage fluctuations, you may presume that the problem is not related to load, but charging. If turning off the L terminal does not stop the fluctuations, there is a high probability that some electrical load is causing the fluctuation.

Sounds like a component problem- needs to be isolated- but this can be tough to do-- I would say it is a big amp draw somewhere- like a big motor- either a blower motor or perhaps the starter- try it with the blower turned off- see if that helps-- could also be the rear defrost- or electric seats etc- so pull those fuses or circuit breakers separately-- the starter may be arcing inside at the solenoid contacts- this I would try last- unfortunately aboutt he only way to isolate it- is to change it out.....good luck...keep us informed

I appreciate the responses so far!! Thank you VERY much guys!! Going to try some this week ......will let you know what happens

PS -this is a FULLY LOADED LT model so your suggestions did give me some ideas!

Thanks Again

Just want to add to the above posts that it could be the main relays under the hood in the electrical center , or maybe a bad ignition switch.

Ok guys ...an update... first of all their was a persistant problem with the vehicles original alternator when you first started the vehicle all the lights had a rythmic flicker ..did not see gauge flux( did this since the truck was new)just lived with it...it would go away after driving for a while..Alternator needed to be changed and this is when the problems started..i took the replacement one out and replaced that one along with a new battery. cleaned cnnectoins on outside fuse center .Now start up is good but as you drive it seems the voltage output gradually drops..and if i start turning blowers and lights and wipers and load the system down , the volt meter drops dramatically to about 10.5 volts..at night the headlights look dim as if the vehicle is running off the battery..slowly recovers as you shut things back off...Driving me nuts!!!!! any more sugguestions???!!!

Welcome Aboard!

There are a few easy, but critical items to check.

First, the main auxiliary power stud on the front of the underhood electrical center should be checked for clean and tight cables. The stud connects the main power buss to the battery/vehicle power, so the lower (buss) connection should also be inspected.

Second, the main body power fuses in the electrical center should be checked for clean connections. These are the large 60A (and maybe 80A) Maxi fuses. The blades can become corroded and cause resistive connections.

Next, the battery power and ground cables need to be checked, not only for clean and tight connections at both ends as you already have, but for damage along the cables' lengths.

Also, the smaller electrical connector at the alternator itself should be checked. This is the alternator regulator's Load, or "L" terminal. This terminal is connected to the PCM to regulate when the alternator is allowed to charge. If the connection between the PCM and alternator L terminal is not intact. the alternator will not output voltage. If that circuit is intermittent, the symptoms you describe can occur.

Finally, if you have access to a bi-directional scanner, you can both monitor AND command the PCM output to the alternator L terminal via the scanner. This may provide a good indication of whether the problem is on the charging side or load side of the system. If turning off the L terminal output stops the voltage fluctuations, you may presume that the problem is not related to load, but charging. If turning off the L terminal does not stop the fluctuations, there is a high probability that some electrical load is causing the fluctuation. Read this quote about the L terminal and the battery connections , either that or your alternator is bad or the ground from the battery to the engine has a bad connection. There is also a ground wire that runs from the engine to the chassis , I think it is located at the back of the head ? you could check those. Charge the battery fully and run it with the battery wire disconnected from the alternator and see if it fluctuates then , if not you could switch to a single post alternator if you cannot get a good supply from the L wire or at least isolate an area of the problem. Also check the connection on your starter , the positive battery cable goes there first and feeds from there to everything else.