Code Reader question...

I just ordered a code reader, even though my "Check Engine" light is not on. I'm wondering if this will tell me what the "parasitic" drain on my battery is or if I'm wasting my money. This is the most frustrating thing I've ever encountered with a car!

It is still a good thing to have, but, I doubt if it will help you with this problem. You might want to advise year of truck, motor type etc.
If it is a OBDI type of computer all it will do is search for stored codes. Won't find shorts etc. A newer type system OBDII, might generate some kind of code if voltage is low MAYBE, but I doubt it. Advise the folks here what you have for better answers. May have a weak alternator, bad voltage regulator, bad battery, etc. This has to be determined by correct testing using meters. Be sure to get the right code reader for your truck. I think 95+ is OBDII, older OBDI, takes different chekcers for codes. Can get the alternator /battery tested for free at Advance..

Sorry. My Blazer is a '96 4.3L midsize. It has 163K miles (give or take). I ordered a OBDII. Another question...would it tell me if there is a problem with the fuel pump? Mine is kinda loud. My dad said a bottle of gas treatment might quiet it a bit, but I haven't been able to drive it a lot because of the oil leak and battery problem. I'm two seconds from parking this truck in the "bad" section of town and leaving it unlocked! (just kidding) That's how frustrated I am with it.

if its OBD1 dont count on the code reader to do much but spit codes at you via the check engine light.

I do not know for sure as all of my vehicles are OBDI, except for the old ladies Intrepid, BUT, generally fuel pressure is a test only done with a pressure tester. A loud pump is not uncommon, unless it was quiet before and became loud. Might want to replace filter if not done in a long time, as that will cause trouble if you don't. Generally, code readers do just that, read trouble codes. It can tell if a sensor has had an issue but not likley to help you with these two problems. If it were mine, I would get what I could checked at Advance (including codes) for free. Then borrow or buy a pressure tester. If the pressure is OK and you replace the filter I would keep running until it quit. Mine is loud, but it was from day one. I am sure others will add more to this.

Thanks for the advice!

if you ordered a code reader that is what you got, not a diagnostic computer, code reader spits codes, no functional tests, no extras

96 is obd2 isnt it?

96 is an OBDII system. 95 and before were OBDI.

I use a scan tool, which gives more detailed information, such as volts, idle speed, sensor data etc. but it is only OBDI rated. Does help a lot. The only way I could possibly see a code checker helping right now would be if OBDII listed a low volt code etc. but I doubt this is possible. Still though a code reader will help you down the road. Suggest a fuel pressure guage, a service manual, and a good mulitmeter to help later on.

hmm.I have 2 95's that are obd2. As luck has it .mine must have been made late in the year cause people dont believe i have obd2 on the 95's till i show them

That's right, I have heard on this forum that there were a few 95's that had OBDII. I guess they are the later engines.

96 obd2 was manditory

I just ordered a code reader, even though my "Check Engine" light is not on. I'm wondering if this will tell me what the "parasitic" drain on my battery is or if I'm wasting my money. This is the most frustrating thing I've ever encountered with a car!


To check for draw on a battery, a quick and easy way to determine which circuit is at fault, try the following procedure: Disconnect the negative battery cable at the battery. Connect the alligator clip of a 12 volt test light to the negative battery post and the other end of the test light to the negative battery cable. With a fully charged battery: If the test light comes on dim, it is indicating normal parasitic draw, (KAM or keep alive memories). If the test light comes on full brightness, you have a 12 volt draw that can drain the battery rapidly. Start pulling fuses one by one until the light either goes dim or out completely. Now you know what circuit to trace. If you're not sure if the test light is at full brightness, open a door, blow the horn etc... something to create a known draw on the battery. If the light doesn’t get brighter, something else is trying to draw current from the battery. I might add that during your test, make sure ALL lights, accessories, and the ignition switch are off, and the doors are closed, or at least hold the pillar switch in, or disable it. NOTE: This test can be done more acurately with a multimeter that has amperage testing capabilities, connected in the same manner as described above. Rule of thumb is anything more than approximately .2 amps will kill a good battery overnight. Your neighborhood dealer will have the normal parasitic draw specifications for your vehicle, whether they give them to you is another story.

To check for draw on a battery, a quick and easy way to determine which circuit is at fault, try the following procedure: Disconnect the negative battery cable at the battery. Connect the alligator clip of a 12 volt test light to the negative battery post and the other end of the test light to the negative battery cable. With a fully charged battery: If the test light comes on dim, it is indicating normal parasitic draw, (KAM or keep alive memories). If the test light comes on full brightness, you have a 12 volt draw that can drain the battery rapidly. Start pulling fuses one by one until the light either goes dim or out completely. Now you know what circuit to trace. If you're not sure if the test light is at full brightness, open a door, blow the horn etc... something to create a known draw on the battery. If the light doesn’t get brighter, something else is trying to draw current from the battery. I might add that during your test, make sure ALL lights, accessories, and the ignition switch are off, and the doors are closed, or at least hold the pillar switch in, or disable it. NOTE: This test can be done more acurately with a multimeter that has amperage testing capabilities, connected in the same manner as described above. Rule of thumb is anything more than approximately .2 amps will kill a good battery overnight. Your neighborhood dealer will have the normal parasitic draw specifications for your vehicle, whether they give them to you is another story.

That is excellent information! Someone might want to post this in the forum's how to section.