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1993 blazer s-10 trans shift problems


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1dodge1mopar
User

Sep 30, 2006, 9:01 PM

Post #1 of 4 (2029 views)
1993 blazer s-10 trans shift problems Sign In

i have a 93 blazer s-10. i have replaced the alternator. according to CHILTON i have an s-10 with electronic cont'd trans. when i drive with the lights on, it will show batt discharging and downshift down to lower gear. the first time it happened, i was on I-80 to Mo. @ 75 mph, with lights on for about 5 mins, then, downshift to LOW (i think because of the high whine). it has happened when i've used my turn sig's and turned the radio on, at lower speeds. when i noticed the amm ga dropping with lights on, i suspected a bad volt reg. i checked the volt o-p on the alt and found a fluc'n of 9.4 to 13.6-i bought a new alt.-still displays the same problem(DOWNSHIFTING WITH LIGHTS ON). the CHILTON manual mentions a solenoid "mounted in the outdrive housing" of the trans but does not show it's location, if reachable from the o/s. it shows a "powertrain control module" in the wiring diagram for the "W" engine. i took the s-10 to the dealer. they told me to "get a new computer" because mine "would not communicate" with thei4r diagnostic system. i did but the problem still exists. HAS ANYONE OUT THERE COME ACROSS THIS PROBLEM? if so, will you PLEASE! help me, or steer me in the right direction.--THANX--p.s.--i have driven some times in town at speeds up to 50 mph(on an industrial road!) with no downshift?????


steve01832
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steve01832 profile image

Oct 1, 2006, 2:49 AM

Post #2 of 4 (2021 views)
Re: 1993 blazer s-10 trans shift problems Sign In

Did the dealer tell you that the new computer still can't communicate with their equipment? Is the charging problem resolved or is that still acting up too? I'm curious to know if they replaced the ECM or if they just updated the software (replaced PROM and MEMCAL) or did both. Post back so we can go further.

P.S. Let's tackle the charging problem first. Charge the battery and get that load tested to make sure it's good. The running voltage should be at 14.0 - 14.6 v across the battery terminals. If the voltage is too low ALL ELECTRONIC COMPONENTS WILL BE AFFECTED.


1dodge1mopar
User

Oct 1, 2006, 4:36 PM

Post #3 of 4 (2016 views)
Re: 1993 blazer s-10 trans shift problems Sign In

STEVE-thanx for the comeeback on my problem. to update you: "I" changed the computer(ecm) and the PROM myself. i do not know what the "memcal" is. i did not go back to the dealer because i spent almost 4 hrs at the shop trying to get someone just to look at/check out the problem. i did raise some hell after being there 2 hrs and my blazer hadn't even moved. after i replaced the alt with a lifetime "rebuilt" model, i immed checked the volt out:13.2-13.8 after i installed. that was about 3 wks ago. it is 13.02-13.04 alt out and 13.07-13.08 across batt terms. it runs fine without the lights and the amm holds mostly just under the "14" on the amm ga but occasionally will go over 14 and hold, changing from time to time back to just under 13 when i use my turn signals. if you need anymore info, please post or email me(may be faster-direct pc-pc link) @ luvmykidz_famly@hotmail.com--THANX


steve01832
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Oct 2, 2006, 5:32 AM

Post #4 of 4 (2011 views)
Re: 1993 blazer s-10 trans shift problems Sign In

The 13 volts with engine running has got me concerned. Running voltage has to be above 14 volts but less than 15 volts. Start by charging the battery and cleaning and retightening the battery cables. Have it load tested by a shop. If it checks out OK then start the car and check the voltage across the battery terminals with a digital voltmeter. It should be somewhere around 14.6 volts. If it is not, put the meter across the battery terminals and have someone turn on the headlights, high beams, A/C or heat to high, rear window defrost if equipped. As these loads are turned on watch the meter. If the voltage drops as they are turned on 1 by 1 then try a different alternator.( I have had many bad rebuilds in my 18 years in the field). If the voltage holds steady at 13- 13.5 volts post back and I'll walk you thru a voltage drop check. Please let me know either way.
P.S. The above test has to be done with the engine running. Use caution around belts and fan and watch the meter leads that they don't get caught up in moving parts. SAFETY FIRST.

Steve


(This post was edited by steve01832 on Oct 2, 2006, 5:38 AM)






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