I have a charging problem with my old 1995 Ford Ranger. I just bought new idler pulley and alternator but it did not fix the problem. I had to jump start the truck a few times because the battery was only 12.1vdc. I checked battery voltage with truck running and had 14.2vdc a few days ago. My check engine light, battery voltage indicator, and charge light were working fine. After troubleshooting possible alternator problem I lost check engine light, battery voltage indicator light, and voltage indicator needle is now to the far left and dose not work with truck running. I replaced alternator and still no charging voltage present on cables with truck running. I have checked continuity from alternator to multi pin connector in left front engine compartment. Fusable link to starter solenoid is good. I think I may have a short or open in the malfunction indicator in instrument cluster. Do you have any suggestions for my problem?
Measure the voltages on the wires that plug into the generator. The yellow one must have battery voltage all the time. If it is missing, look for a blown 15 amp fuse. The green / red wire should have around 2.0 volts when the ignition switch is on. If you find 0 volts and the battery light is not on, check that wire back to the dash for a break in the circuit. If you find full battery voltage, check that plug for a bad connection. If it's good, suspect a defective voltage regulator.
February, 17, 2011 AT 3:28 AM
Thank you for the reply.
Today I verified voltages comming from alternator 3 pin plug conn 12vdc at teminal A, 11 volts at terninal I lt green/red wire to ignition switch, and terminal S blk/white plug to stator has continuity. I think it my be the ignition switch, or starter relay has broken internal switch to allow alternator too charge after voltage is sent to starter motor when key is in start position. I removed the instrument cluster and checked all bulbs and cleaned it. I tried to trace the wires to the charge indicator and internal voltmeter but got lost in a sea of harness. An electrician friend told me to check the starter relay. Could I have damaged it or shorted it out? It seems like my computer is not working now it runs poorly and only on the battery voltage. No charge current in my cables. I removed and filed all ground to engine and body and verified continuity with meter. Is it possable that I have a pad PCM diode in power distribution box? How do I test it? Cann the starter seloniod be bad? How do I test it? Can it be my loose ignition switch, it has been working fine before. THe ignition switch seems hard to remove, is it a possable suspect? Any help from a mastermind mechneck would be greatly appreciated. 94' 2.3 ranger
February, 17, 2011 AT 3:58 AM
12 volts on the green / red wire with the engine running and the dash light is off means the regulator is putting that voltage there to turn the light off. It does that when it thinks the system is working. As further proof, measure the voltage on the short white / black wire while the engine is running. If the generator is working there will be near 6 volts on it.
Measure the voltage on the fat output wire while the engine is running. If it is real high, say 15 volts or more, there is a break between that point and the common tie point on the starter solenoid.
February, 17, 2011 AT 4:44 AM
Thanks for the reply. I really appreciate the insightful information in helping me get through this. I will check tomorrow to see if I have a high dc output and if the generator is working properly.