weather car wont start and radio keyless entry power windows

When the weather is hot and the sun is shining, the car fails to start, and the radio, keyless entry, power windows, power locks, and power seats do not function. However, after sunset, everything operates normally. It is important to check if the headlights work during the malfunction. The issue may lie in the connections between the battery and the fuse blocks or another component in the circuit. The main connections from the battery to the fuse blocks appear to be intact, which suggests that the ignition or associated circuits may be the source of the problem. The fact that the AC fan and wiring function adds complexity to the diagnosis. The starting circuits, including the IGN E fuse, are critical as they provide power when the key is in the Run or Start position. A loose connection or corrosion in the underhood fuse block could be the culprit. Without a multimeter, a visual inspection of the underhood fuse block for loose fuses or wiring is recommended. During the hot weather, checking the voltage at various fuses in the underhood block could provide insights. Additionally, the front wipers draw power from a different fuse block than the front circuits, and the horn is likely powered from a source that bypasses the Run/Start circuit. If the vehicle has automatic AC controls with a temperature display, this may be relevant to the troubleshooting process. The situation is complicated by the fact that the sun obscured the issue temporarily. A comprehensive list of non-functional components during the problem occurrence may be useful. Creative methods, such as using a hairdryer to apply heat, can help replicate the issue. The Body Control Module (BCM) manages the keyless entry, power windows, and locks, and the relevant schematic should be consulted. A thorough inspection of each fuse block, particularly under the hood and at the rear, is advised. Observations of erratic behavior, such as the security and ABS lights activating intermittently, might indicate a deeper issue. Applying heat to the components could help pinpoint the problem, but disassembly may be necessary for a thorough investigation. Caution is advised during this process as the issue may resolve itself unexpectedly.

The described electrical issue indicates a potential thermal-related fault affecting multiple systems in the vehicle. The symptoms suggest that high temperatures may be impacting the integrity of electrical connections or components, particularly those associated with the fuse blocks and the Body Control Module (BCM).

To analyze this situation, a detailed understanding of the vehicle's electrical schematic is essential. The battery provides power to various components through multiple fuse blocks, with the underhood fuse block being critical for starting and ignition functions. The IGN E fuse is particularly important as it supplies power when the key is in the Run or Start position. If this fuse or its connections are compromised, it could lead to the symptoms described.

A systematic approach to troubleshooting is recommended. This includes:

1. **Visual Inspection**: Examine the underhood fuse block for any signs of corrosion, loose connections, or damaged fuses. Pay special attention to the integrity of the fuse sockets.

2. **Voltage Testing**: Without a multimeter, a simple test can be conducted by checking for voltage at the fuses during the hot weather condition when the car fails to start. This can help identify if power is reaching critical components.

3. **Thermal Testing**: Using a hairdryer or similar device, apply controlled heat to the fuse blocks and associated wiring while observing if the vehicle's systems start functioning. This can help isolate the component that may be failing under heat stress.

4. **Component Isolation**: Investigate the wiring from the battery to the fuse blocks and the connections to the BCM. Checking for continuity and ensuring that all grounds are secure is crucial.

5. **Schematic Reference**: Utilize the vehicle's electrical schematics to trace circuits and understand the interdependencies between various systems, including the AC fan, wipers, and horn. This can provide insights into whether the problem is localized or systemic.

6. **Documenting Findings**: Keeping a detailed log of which systems fail and under what conditions can assist in identifying patterns and potential solutions.

By following these steps, a clearer understanding of the underlying issue can be achieved, leading to a more effective resolution of the vehicle's electrical problems.When the weather is hot with the sun beating down the car won`t start and radio, keyless entry, power windows, power locks, radio, and power seat wont work. After the sun sets everything functions again. Have you checked to see if the headlights function when the problem occurs What I am trying to figure out is if it is a problem between the main

connections between the battery and the fuse block(s), or some other component down the line. It sounds like the main connections between the battery and fuse block(s) are probably OK. That would usually lead us to the ignition or circuits, but since the AC fan & wires work, that adds a twist. If you look at the schematic below, it shows the starting circuits, and the IGN E fuse (at the top left).

This is the main part of the circuit that gets power when the key is in either the Run or Start position. Everything else comes from the battery. Let me see if I can track that down a little more. What I am suspecting is that there is some loose connection in the underhood fuse block, perhaps some corrosion in the fuse sockets that are there, based on what you have told me.

If you don`t have meter, I would take a look at the underhood fuse block to see if you can observe anything obvious such as any loose fuses or wiring in that area. I think what you will be doing, while it is hot, is checking the voltage at various fuse in the underhood fuse block for power.

It could also be that one or more of the connections at the bottom or side of the fuse block has a problem. Here are some schematics I have gathered so far. I have not traced each of these down yet, but I do see that the front wipers get their power from a different fuse block (rear) than the front one.

I will be hunting down the horn & AC fan to see how they are different, but I am pretty sure the horn is powered from a source that does not go through the Run/Start circuit, so I will go for the AC fan first. Do you have Automatic or Manual AC controls Automatic usually has a temperature display that can be set, while Manual only has a knob that moves from cold to hot.

it has manual AC controls. another complication is that the sun went behind the clouds so the car is starting now. thats the problem the dealership had was that we didn`t know it was a thermal problem at the time so they couldnt get it to act up wheile that had it in the shop. Maybe it would be best if I have a list of what does NOT work when the problem occurs I have the list from your first message, is there anything else that should be on the list Oh - almost forgot.

Sometimes we have to "get creative" to recreate these problems. I know is may sound crazy, but we have even used hair driers (or something like them) to heat things up to try and isolate problems. The Keyless entry & power windows and locks are all controlled by the Body Control Module (BCM) so here is the schematic for that, showing which fuses are used.

What I would suggest is a very thorough inspection of each fuse block and then try to heat them up to see if you can get them to fail. I would start with the underhood fuse block, but I would also look at the rear one too. Well it did some of it`s other weird stuff today. While driving it the security and ABS light came on and the bell chimed then would go off. This happened several times this afternoon. This is the kind of thing that it did last year while driving before it manifested the no starting problem.

I think you will have to start with applying heat to try to get an idea of where the problem may be. But after that, I believe at least some disassembly will be required. Just try to do it carefully. What could happen is that it will start working again during this process. Again, this could take some time and could be a bit frustrating at times, so just be ready for that. I heated both fuse blocks with the blow dryer and everything still started fine. I loosened the bolts that stand u 🔗 External reference