97 Taurus won't crank (long post)

Sorry that this is kind of long. Last week my sister's 97 taurus wouldn't start. The initial problem was that the car would not crank. After three people tried to jump start it, she called me. She said after they tried to help her, the horn was blowing and they could not get it to stop. She left the vehicle with horns blowing, and relays buzzing and chattering. When I returned with her, the battery was dead. I cleaned the battery terminals and got it started and took it home (about a mile away). The speedometer, odometer and radio were not working. Additionally the horn would not sound. Found one blown fuse in the passenger compartment that fixed the speedometer/odometer/radio problem. Also, found a 20A fuse in the main distribution box in the engine compartment that went to the horn was blown. Replacing the fuse resulted in it blowing again when the horn button was activated. Testing found two bad horns (low pitch and high pitch - clicks but won't sound with 12V directly connected to them). Replaced the battery (one in there was seven years old) for good measure. I suspect that one of the people who tried to help my sister jump it conected the terminals reversed and blew the fuses.

After replacing the fuses and the battery, I got the vehicle started and seemed to run just fine. Upon returning home, I put my tools away and figured I had most of the problems solved. I suspect the horns blowing burned them out after a couple of hours (if the battey lated that long). Anyway they are bad now. Unfortunately, the problems were not fixed in that after test driving it, I found that it would not crank when I attempted to restart it. All the right dash lights seem to come on, the doors will lock but the engine will not crank. I traced the start relay primary circuit and there is no voltage coming out of the start terminal on the ignition switch. I can jump 12V to this circuit and the starter activates. I can disconnect the battery cable, wait a few minutes and reconnect it and the car will start and run just fine. If I turn it off and immediately restart it it works just fine. If I turn it off and wait a few minutes, it will not crank - until I remove the battery cable and wait a few minutes. I suspect that this might have been the initial problem prior to the people trying to help her jump it but this condition could also be due to whateve they did to blow the fuses.

The car has a dealer installed (Ford unit) keyless entry system and the there is a connector under the steering column that the dealer said worked in conjunction with some kind of anti-theft device that he tried to sell her, although she didn't buy it. I suspect that something in the anti-theft or keyless entry systmem is inhibiting the start circuit but have no real electrical schematic other than the notional ones supplied in the Haynes repair manual. The schematic diagrams I have show nothing in the starter primary starer circuit that could cause this problem but they are not exact for the 97 Taurus. Any ideas? Thanks.

Mike

Ok, this certainly seems to be a problem with the starter primary circuit. You are on the right track with suspecting the after market keyless entry system, can you temporarily disconect all or part of this set up and see if the problem disappears?

Here's an update: I spoke with my sister who tells me that she had to use the "start switch" often to get the car to start. I asked "what start switch?" She replied, "the one under the dash, of course." It seems that there is more of a history to the problem than what I had known. The connector under the dash was part of a anti-theft kill switch that the dealer wanted around $500 for. They install them in each car they get on the lot because it appears it only costs a few dollars to manufacture and can be installed in five minutes. Once it is there they suggest it is a factory option and apparently have good success selling them. Anyway, it wasn't hooked up because she declined to purchase it. I removed it completely.

The start switch she was talking about is some kind of override to the remote door entry unit which appears to have anti-theft features as well. It interrupts the starter circuit and prevents the vehicle from cranking, I suspect, unless the door is opened with the remote or the key. I figure if it is opened by the inside door handle, the unit interprets that as a theft. Unfortunately, it never was installed properly by the dealer. Apparently, she has been using that override switch to get the car started ever since she bought it. Really, she is a smart person - she just knows nothing about cars. The trunk release wire wasn't hooked up. Neither are some of the other features. It will only unlock the car and apparently interrupt the starter circuit. She still had to lock the car with the door switch or the key. They also managed to connect it into the wiring harness in such a way as to disable the hazard warning lights. All connections were made with big balls of black electrical tape. It is the most unprofessional electrical installation I have ever seen and I would have expected Ford to maintain some sort of quality control over they dealer installed options. I guess not.

Anyway, I can make the car work by bypassing the unit but my current goal is to get the car back to factory specifications on the wiring and then reinstall the remote entry unit properly. I don't have installation instructions but there is a pinout on the back of the unit and I do have a good wiring diagram for the car now. If that doesn't work, I'll buy an aftermarket one from Circuit City or Bestbuy and put that in.

By the way, I found that Autozone.com has vehicle-specific service manuals online. I was able to download most wiring diagrams and other service information on the car at no cost. The list of vehcles available looks pretty complete.

Mike

Thank you mpcarr2001. I found everything that I was looking for on repairing my '97 Taurus at autozone's website. Good link!